EP4721354A1 - Phase noise pre-compensation - Google Patents

Abstract

An apparatus may be configured to : determine to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receive, from the second apparatus, at least one signal; and perform the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal. An apparatus may be configured to : transmit, to a second apparatus, at least one signal; and receive, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

Description

PHASE NOISE PRE-COMPENSATION

TECHNICAL FIELD

[0001] The example and non-limiting embodiments relate generally to phase noise and, more particularly, to compensation of phase noise.

BACKGROUND

[0002] It is known, in cellular communication, to post compensate for phase noise based on a phase tracking reference signal.

SUMMARY

[0003] The following summary is merely intended to be illustrative. The summary is not intended to limit the scope of the claims.

[0004] In accordance with one aspect, a first apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: determine to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receive, from the second apparatus, at least one signal; and perform the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[0005] In accordance with one aspect, a method comprising: determining, with a first apparatus, to perform phase noise pre- compensation of at least one signal to be transmitted to a second apparatus; receiving, from the second apparatus, at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[0006] In accordance with one aspect, a first apparatus comprising means for: determining to perform phase noise pre- compensation of at least one signal to be transmitted to a second apparatus; receiving, from the second apparatus, at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[0007] In accordance with one aspect, a non-transitory computer- readable medium comprising program instructions stored thereon for performing at least the following: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[0008] In accordance with one aspect, a computer program comprising instructions stored thereon for performing at least the following: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre- compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[0009] It may be noted that the first apparatus may be/comprise a TX point/TX, while the second apparatus may be/comprise a RX point/RX.

[0010] In accordance with one aspect, a first apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: transmit, to a second apparatus, at least one signal; and receive, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[0011] In accordance with one aspect, a method comprising: transmitting, with a first apparatus to a second apparatus, at least one signal; and receiving, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[0012] In accordance with one aspect, a first apparatus comprising means for: transmitting, to a second apparatus, at least one signal; and receiving, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre- compensated based, at least partially, on the at least one transmitted signal.

[0013] In accordance with one aspect, a non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[0014] In accordance with one aspect, a computer program comprising instructions stored thereon for performing at least the following: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[0015] It may be noted that the first apparatus may be/comprise a RX point/RX, while the second apparatus may be/comprise a TX point/TX.

[0016] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings, wherein:

[0018] FIG. 1 is a block diagram of one possible and non- limiting example system in which the example embodiments may be practiced; [0019] FIG. 2 is a diagram illustrating features as described herein;

[0020] FIG. 3 is a diagram illustrating features as described herein;

[0021] FIG. 4 is a diagram illustrating features as described herein;

[0022] FIG. 5 is a diagram illustrating features as described herein;

[0023] FIG. 6 is a diagram illustrating features as described herein;

[0024] FIG. 7 is a flowchart illustrating steps as described herein;

[0025] FIG. 8 is a flowchart illustrating steps as described herein;

[0026] FIG. 9 is a flowchart illustrating steps as described herein; and

[0027] FIG. 10 is a flowchart illustrating steps as described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0028] The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3GPP thirdgenerationpartnershipproject

5G fifthgeneration 5GC 5G corenetwork

ACLR adjacentchannelleakageratio

ADC analogtodigitalconverter

AMF accessandmobilitymanagementfunction

BW bandwidth

CBW carrierbandwidth

CP cyclicprefix

CPE commonphaseerror cRAN cloudradioaccessnetwork

CU centralunit

DCI downlinkcontrolinformation

DFT-s-OFDM phasenoisepre-compensation

DL downlink

DMRS demodulationreferencesignal

DU distributedunit

EE energyefficiency eNB (oreNodeB) evolvedNodeB (e.g.,anLTE basestation)

EN-DC E-UTRA-NR dualconnectivity en-gNB orEn-gNB nodeprovidingNR userplane and controlplaneprotocolterminations towardstheUE,andactingassecondarynodeinEN-DC

E-UTRA evolved universal terrestrial radio access, i.e.,the LTE radio access technology

EVM errorvectormagnitude

FD full-duplex

FDRA frequency-domainresourceallocation gNB (orgNodeB) base station for5G/NR,i.e.,anodeprovidingNR userplaneand control plane protocolterminationstowardsthe UE,and connected via the NG interfacetothe5GC

ICI inter-carrierinterference

I/F interface KT known-tail

LI layer1

LO localoscillator

LTE longterm evolution

MAC medium accesscontrol

MCS modulationandcodingscheme

MIMO multiple-inputmultiple-output

MME mobilitymanagemententity ngorNG new generation ng-eNB orNG-eNB new generationeNB

NR new radio

N/W orNW network

OBO PA output-backoff

OFDM orthogonalfrequencydivisionmultiplexing

OOB out-of-bandradiation

OOK on-offkeying

O-RAN openradioaccessnetwork

P2P point-to-point

PA poweramplifier

PAPR peaktoaveragepowerratio

PDCP packetdataconvergenceprotocol

PDCCH physicaldownlinkcontrolchannel

PDSCH physicaldownlinksharedchannel

PHY physicallayer

PN phasenoise

PRB physicalresourceblock

PRS positionreferencesignal

PSD powerspectraldensity

PTRSorPT-RS phasetrackingreferencesignal

PUCCH physicaluplinkcontrolchannel PUSCH physicaluplinksharedchannel

RAN radioaccessnetwork

RE resourceelement

RF radiofrequency

RLC radiolinkcontrol

RRC radioresourcecontrol

RRH remoteradiohead

RS referencesignal

RU radiounit

Rx receiver

SC singlecarrier

SC-FDE singlecarrierwithfrequencydomainequalization

SCS subcarrierspacing

SDAP servicedataadaptationprotocol

SE spectralefficiency

SGW servinggateway

SISO single-in-single-out

SMF sessionmanagementfunction

SNIR signal-to-noiseplusinterferenceratio

SNR/SNIR signal-to-noiseratio

SRS soundingreferencesignal

SSB synchronizationsignalblock

TBoMS transportblockovermultipleslots

TDD timedivisionduplex

TDRA timedomainresourceallocation

Tx transmitter

UE userequipment(e.g.,awireless,typicallymobiledevice)

UL uplink

UPF userplanefunction

UW uniqueword VNR virtualizednetworkfunction

[0029] Turning to FIG. 1, this figure shows a block diagram of one possible and non-limiting example in which the examples may be practiced. A user equipment (UE) 110, radio access network (RAN) node 170, and network element (s) 190 are illustrated. In the example of FIG. 1, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. A "circuit" may include dedicated hardware or hardware in association with software executable thereon. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways. The module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120. The module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

[0030] The RAN node 170 in this example is a base station that provides access by wireless devices such as the UE 110 to the wireless network 100. The RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as either a gNB or a ng-eNB. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to a 5GC (such as, for example, the network element(s) 190). The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit (RU). The gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the Fl interface connected with the gNB-DU. The Fl interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the Fl interface 198 connected with the gNB-CU. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station, access point, access node, or node.

[0031] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N/W I/F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory/memories and processor(s), and/or other hardware, but these are not shown.

[0032] The RAN node 170 includes a module 150, comprising one of or both parts 150-1 and/or 150-2, which may be implemented in a number of ways. The module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152. The module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 150 may be implemented as module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations as described herein. Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

[0033] The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0034] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH/DU, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU) of the RAN node 170 to the RRH/DU 195. Reference 198 also indicates those suitable network link(s).

[0035] It is noted that description herein indicates that "cells" perform functions, but it should be clear that equipment which forms the cell will perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single base station's coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the base station has a total of 6 cells.

[0036] The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and/or a data communications network (e.g., the Internet). Such core network functionality for 5G may include access and mobility management function(s) (AMF(s)) and/or user plane functions (UPF(s)) and/or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (Mobility Management Entity)/SGW (Serving Gateway) functionality. These are merely illustrative functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to a network element 190. The link 131 may be implemented as, e.g., an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N/W I/F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the network element 190 to perform one or more operations. [0037] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network- like functionality to software containers on a single system. For example, a network may be deployed in a tele cloud, with virtualized network functions (VNF) running on, for example, data center servers. For example, network core functions and/or radio access network(s) (e.g. CloudRAN, O-RAN, edge cloud) may be virtualized. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

[0038] It may also be noted that operations of example embodiments of the present disclosure may be carried out by a plurality of cooperating devices (e.g. cRAN).

[0039] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi- core processor architecture, as non-limiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, and other functions as described herein.

[0040] In general, the various example embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

[0041] Having thus introduced one suitable but non-limiting technical context for the practice of the example embodiments of the present disclosure, example embodiments will now be described with greater specificity.

[0042] Features as described herein may generally relate to phase noise. Phase noise (PN) originates mainly from local oscillators in the up and down conversion. Usually in the orthogonal frequency division multiplexing (OFDM) based systems (including DFT-s-OFDM), the PN impact manifests in a form of common phase error (CPE) which is common for all subcarriers, and inter carrier interference (ICI), which is basically unique for each carrier. The impact may depend, especially, on the subcarrier spacing. PN and ICI compensation may be required to enable the communication with these waveforms.

[0043] The PN spectrum typically depends on the used oscillators, and its effect depends on the signal bandwidth (or symbol rate), among other factors e.g. in the implementation. PN can often be modelled by a simple combination of correlated PN component (e.g. Wiener type or other) and uncorrelated component (White Gaussian type of PN). The threshold for the dominant factor between gaussian and Wiener type can be approximated as:

[0044] where N is the number of symbols (samples),f_c is the oscillator corner frequency, and T is the symbol duration (see, e.g., S. Bicais and J. -B. Dore, "Phase Noise Model Selection for Sub-THz Communications," 2019 IEEE Global Communications Conference (GLOBECOM), 2019, pp. 1-6, doi: 10.1109/GLOBECOM38437.2019.9013189). If the above condition is satisfied, PN may be appropriately modelled as Gaussian and the uncorrelated component may have the dominant effect, which is the case with larger bandwidth (small symbol period T) e.g. in sub- THz frequencies. Hence, the compensation of the correlated part may have a small effect in the performance in such a case (see, e.g., M. R. Khanzadi, D. Kuylenstierna, A. Panahi, T. Eriksson, and H. Zirath, "Calculation of the performance of communication systems from measured oscillator phase noise," IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 61, no. 5, pp. 1553-1565, May 2014), and the uncorrelated PN part may need to be estimated and compensated. As a result, more reference signals (RS) with a wide bandwidth may be required, since the uncorrelated component cannot be tracked as conventionally (e.g. uncorrelated random phase variation). However, at somewhat lower frequency ranges (e.g. FR3, lower FR2) where PN may still be non-negligible and impacts the performance, the PN may be mainly dominated by correlated components that may be relatively slowly varying over time.

[0045] PN for FR3, FR2 and sub-THz is significant compared to low frequencies in FR1, even with a good quality local oscillators (e.g. gNB). The dominant PN component in FR3-FR2 is mainly the correlated PN component(s), especially with current 5G NR BW (e.g. up to 10s of MHz).

[0046] PN at different frequencies may be seen in PN PSD from the datasheet of a good quality vector signal generator from Keysight Technologies (see, e.g., https://www.datatec.eu/media/pdf/df/22/ef/ldaefdbd-adbf-4ca6- b8e4-71ccea4d424b_e8267d-513_d33kRTG6OkbmHQ.pdf). The PN of a gNB may be similar, and of a UE PN may be much worse.

[0047] More details about PN impact and a more accurate model, mainly where correlated PN is important, may be found in, for example, https://www.edn.com/impact-of-phase-noise-in-signal- generators/.

[0048] Features as described herein may generally relate to the 5G NR phase tracking reference signal (PTRS). PTRS has been introduced in 5G and is only standardized for data channels by release 17; there is no PTRS for control channels (e.g. PDCCH, etc.). For DFT-s-OFDM, the specifications define PTRS, as illustrated in FIG. 2, which includes a table describing a PTRS group pattern as defined in 3GPP TS 38.214 (see, e.g., 3GPP TS 38.214. "NR; Physical layer procedures for data"). The PTRS pattern in each symbol depends on physical resource block (PRB) allocation thresholds (configurable): 'sampleDensity' (320). The PTRS time-domain density (in OFDM symbol-level) is configurable: 'timeDensity-TransformPrecoding' (330).

[0049] Referring now to FIG. 3, illustrated at 310 are PTRS uplink configuration parameters as defined in 3GPP TS 38.331 (see, e.g., 3GPP TS 38.331. "NR; Radio Resource Control (RRC); Protocol specification"). When the timeDensity field is absent for CP- OFDM, the UE may assume a time density of 1. For DFT-s-OFDM, when timeDensityTransformPrecoding (330) is absent, the UE may assume a time density of 1.

[0050] Referring now to FIGs. 4-5, illustrated are examples that show how PTRS may be allocated for DFT-s-OFDM. In FIG. 4, illustrated is an example of a single resource block allocation with 12 subcarriers and 14 DFT-s-OFDM symbols, when a DFT-s-OFDM symbol has two groups of two PT-RSs (430) (FIG. 4 illustrates PTRS locations for each DFT-s-OFDM symbol prior to DFT operation in the transmitter, i.e., in time-domain), and the time-domain DFT-s-OFDM symbol level density (L_ptrs) is 2 (i.e., PTRS pattern is repeated in every second DFT-s-OFDM symbol). In the specification, time- domain symbol level density may also be 1 or 4. In FIG. 5, illustrated is an example of available PTRS patterns for a single DFT-s-OFDM symbol in time-domain according to current 5G specification, when allocation bandwidth is 384REs (32 PRBs). This illustrates how different PTRS patterns map to this specific allocation size in time domain for a single DFT-s-OFDM symbol.

[0051] FIGs. 4-5 illustrate PTRS pattern examples for DFT-s-OFDM with (a) 1 RB and L_ptrs=2 in a slot, and (b) 32 PRB in a single DFT-s-OFDM symbol, according to 5G NR available granularity. Referring now to FIG. 6, illustrated are time density and frequency density of PT-RS for OFDM as defined in 3GPP TS 38.214 (see, e.g., 3GPP TS 38.214. "NR; Physical layer procedures for data"). For OFDM, the specifications define, as illustrated in FIG. 6, PTRS time-density (i.e. in OFDM symbol-level) based on modulation and coding scheme (MCS) (values are configurable), and PTRS frequency- density (RE in each OFDM symbol) based on PRB allocation thresholds (configurable).

[0052] As noted above, PN is more significant at higher frequencies (FR3, FR2 and sub-THz) and even RX post-compensation based on PTRS, when available, may not be sufficient (or not an optimal solution) for maximizing spectral efficiency (SE) and/or energy efficiency (EE) and coverage.

[0053] For example, PN may not be compensated in PTRS-less physical channels (e.g. PDCCH, PUCCH), and these critical channels may be limiting the overall coverage due to uncompensated PN.

[0054] For example, PN post-compensation accuracy using PTRS may rely mainly on the signal-to-noise ratio (SNR) and the density/patterns of PTRS.

[0055] Accordingly, at low SNR, the PN post-estimation accuracy at Rx may be very low and thus the coverage may be more limited with the performance degradation due to PN. At higher frequencies with significant attenuation, and especially in UL with limited UE power, Rx SNR may be very low, leading to low accuracy for PN estimation, and thus UE lower coverage (e.g. significant differences may be noticed compared to ideal PN compensation).

[0056] At high SNR, the PN post-estimation may be more accurate, but it may still not be leading to the optimal performance (e.g. like the case without PN), especially with low PTRS overall density or number of used samples in the estimator.

[0057] More power may be consumed by UE/gNB to reach this high SNR in UL/DL, thus leading to a lower energy efficient system.

[0058] The residual PN after PN post-compensation may always exist, and this may limit the maximum achievable spectral efficiency (i.e. high modulation order may be limited according to residual PN level and waveform/modulation sensitivity). An iterative PN estimator for post-compensation may be used to enhance accuracy, but this may increase the processing latency and the complexity, and this may not be affordable for Rx (e.g. at/for UE) and may still be challenging especially if SNR is not sufficient.

[0059] The number of PTRS per symbol, and even in a slot, may be quite low, and thus may be limiting the PN post-estimation accuracy. A more advanced solution, and a complex PN estimation/compensation algorithm, may be needed at the Rx if the PN in the received signal is very high and not efficiently estimated with simple linear estimator, for example. Any effort to limit the frequency or complexity of the PN estimation/compensation solution would be helpful. [0060] The PN from the Tx oscillator may affect the RF signal quality (error vector magnitude (EVM), adjacent channel leakage ratio (ACLR), out-of-band radiation (OOB), etc.), mainly due to the spectrum regrowth issue. In other words, a higher PN level may lead to higher ACLR and OOB; this impact for the same PN level may be observed at a different carrier frequency (i.e. FR3 or other) (see, e.g., https://arxiv.org/ pdf/2004.11126.pdf).

[0061] In order to satisfy these RF requirements, one could increase 0B0 to operate at a more linear power amplifier (PA) zone so that the allowed margins for these RF requirements could be reserved to live with the existing Tx PN and its RF distortion, rather than supporting some PA non-linearities for higher PA efficiency. This option is at the price of lower PA efficiency, higher power consumption (i.e. lower energy efficiency) or lower output power (i.e. lower SNR, which may result in lower coverage and spectral efficiency/data rates).

[0062] This lower RF signal quality, even when it is within the allowed margins in the specs (mainly for ACLR, OOB) may also affect adjacent user(s) due to the resulting interference that cumulates with larger number of low quality signals. This interference issue due to PN may be more pronounced at lower frequencies of FR3 and FR2, where the attenuation and blockage are not very high, as in sub-THz, and the beamwidth could be covering many adjacent transmitters.

[0063] Note that 5G-NR supports currently OFDM for DL and DFT-s- OFDM and OFDM for UL, and the next generations could add new waveforms in UL and/or DL to be more robust to PN and/or more energy efficient. However, as long as PN exists, these listed problems remain, especially with coherent waveforms/modulations, and its mitigation at Tx may help to achieve good RF signal quality, possibly operate at higher PA efficiency for better energy efficiency, and/or increase spectral efficiency (e.g. allow higher MCS,allow higher MCS (i.e., SE), or higher modulation order than on-off keying (OOK) of extremely low SE, even at high PN level).

[0064] Especially for higher order modulations and mmW/sub-THz frequencies, PN compensation is a challenging task, and UE RF requirements may be defined with either a UE-specific recommended PTRS configuration (UE choice) or a fixed PTRS configuration for all UEs (see, e.g., R4-2217729). This means that the practical performance in the field may be significantly different compared to the test case, and thus more adaptive methods may be needed in practice to enable robust and flexible communications.

[0065] During the design of the local oscillator (LO) and the RF/analog circuit, much effort is spent to limit the PN and RF impairments within a complexity, cost, circuit area footprint, and power budget constraints. Indeed, this PN minimization in the analog domain is up to the product (e.g. gNB, UE) implementation and it is clear that PN PSD may still be significant, even with high quality/cost/size products.

[0066] PN pre-compensation in the analog domain as in A. Zahedi- Ghasabeh et al. "Adaptive Pre-Compensation of Transmitter Phase Noise for User Coexistance in Cognitive Radios", IEEE ICC, 2011. https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5963007 is one possible solution if the aforementioned constraints allow such a technique, as it requires at least a feedback path in Tx architecture in the analog/RF domain. This feedback path and PN pre-compensation algorithm cause additional circuit and computational complexity, and Tx power consumption as highlighted in Zahedi-Ghasabeh et al. In addition, the pre-compensation based on hardware feedback path degrades with analogue to digital converter (ADC) resolution and hardware latency. Moreover, the technique in Zahedi-Ghasabeh et al. blocks any full-duplex (FD) operation if no additional Rx path is added at Tx for this purpose to fit with budget constraints. Note that FD is a possible option currently at the gNB in DL, and it could be a potential option for future UE, for example for sensing purposes.

[0067] In an example embodiment, PN pre-compensation may be based on previous PN estimations at the Tx (UE or gNB) from the opposite link with the same Rx (UE or gNB) when a set of conditions is satisfied and according to assistance signaling.

[0068] In an example embodiment, PN pre-compensation at the Tx may be adaptive, and may consider jointly Tx and Rx PN, in contrast to the state of art technique that addresses Tx PN only. In an example embodiment, assistance information related to Rx PN may be used to determine the relevant signals and make sure that the PN is correlated enough (or dominant). The assistance information may also be used to avoid using improper or outdated PN estimations. A technical effect of example embodiments of the present disclosure may be improved signal quality.

[0069] A technical effect of example embodiments of the present disclosure may be to avoid degrading the performance due to using improper or irrelevant estimated PN values (e.g. PN from other LOs, outdated estimations, etc.). [0070] In an example embodiment, relevant received signals for PN pre-compensation at Tx may be determined. In an example embodiment, the indication (s) of assistance information may be determined. In an example embodiment, the indication of PN pre- compensation (de)activation may be determined.

[0071] In an example embodiment, DL pre-compensation of PN may be performed at the gNB. The gNB may request that the UE provide pre-compensation assistance information. The UE may send assistance information to the gNB. The assistance information may be explicitly or implicitly indicated (e.g. via indices to pre- defined values). The (indication of) assistance information may be transmitted via RRC signaling, uplink control information, UE capability signaling, etc. The assistance information may indicate that pre-compensation should be applied for a specific modulation and coding scheme (e.g. larger than a threshold) or specific subcarrier spacing (e.g. smaller than a threshold). The assistance information may comprise at least one of: a phase noise characteristic, a phase noise consistency indication, a possibly relevant signal, a pre-compensation capability, an indication of an event configured to cause phase noise inconsistency, an indication of a signal passing through a main local oscillator at the second apparatus, at least one modulation and coding scheme to which the pre-compensation is configured to be applied, at least one subcarrier spacing to which the pre-compensation is configured to be applied, or a maximum tolerable phase noise level. The pre- compensation capability may, for example, be a capability of the UE.

[0072] The assistance information may additionally or alternatively include hardware LO architecture details. For example, for a multiple antenna system, there may be a centralized LO for all antennas, or a distributed LO architecture (1 LO per antenna) or hybrid LO architecture (1 LO for a set of antennas/panel and different panels have different LOs). In an example embodiment, this information may be needed to perform PN pre-compensation.

[0073] Alternatively or additionally, the UE may request that the gNB perform pre-compensation of PN. This may be done, for example, due to power-saving reasons to enable simpler (or no) PN post-compensation, or to avoid SNR degradation. The request may also be meant for specific modulation and coding schemes (e.g. certain high MCSs), subcarrier spacings (e.g. for smaller SCSs), or PTRS configurations (e.g. low overheads). The request may include, for example, a pre-compensation capability of the UE.

[0074] In an example embodiment, the contents of the assistance information may be part of the request, and/or vice versa.

[0075] The gNB may determine when PN pre-compensation is applicable and may be used based on received indications (e.g. assistance information) and earlier UL signals. The UE may receive an indication from the gNB that the PN pre-compensation is used or not. The PN pre-compensation may be indicated for certain time duration(s) and/or periodically. The gNB may apply PN pre- compensation to the scheduled downlink signal. This may have the technical effect of lowering the EVM of the signal (i.e. the UE may expect that it will receive better quality signal).

[0076] In an example embodiment, UL pre-compensation of PN may be performed at the UE. [0077] In an example embodiment, the Tx and the Rx may indicate some assistance information (e.g. PN characteristics, etc.) to each other. The Tx may determine relevant received signal(s) to perform PN pre-compensation and possibly new PN estimation, if relevant. The Tx may perform PN digital pre-compensation (e.g. non-analogue pre-compensation) for the overall Tx and Rx PN. The Tx may indicate to the Rx when the Tx PN pre-compensation is (not) performed. The Rx may indicate to the Tx about PN pre-compensation accuracy (e.g. indicator related to observed new PN level at Rx after pre-compensation has been applied), or the Rx may request to activate or adapt Tx PN pre-compensation (e.g. as part of feedback).

[0078] In some circumstances, for example a single-in-single-out (SISO) timed division duplex (TDD) communication, with one LO at transmission (Tx) and one at receiving (Rx) in a UE, the assistance information may not be needed. The Tx, especially if it is a UE, may perform PN pre-compensation using the relevant signal(s) from the other apparatus (e.g. gNB) since they are expected to be from the same LOs (e.g. one LO at each apparatus is the same for transmission and reception (TDD)) and UE knows its PN characteristics, which is usually the dominant part. In such an example, the information known at the same LO may be considered the assistance information. In such an example, the Rx PN of the gNB may be negligible (i.e. less than a predetermined threshold value).

[0079] Referring now to FIG. 7, illustrated is a signaling diagram for Tx PN pre-compensation at an access node for DL signals. The access node may be, for example, a base station, a gNB, a 6G nodeB, etc. In other words, the access node may act as the Tx, while the UE may act as the Rx. At 705, the UE/Rx may optionally transmit earlier UL signals to the access node/Tx (e.g. physical uplink shared channel (PUSCH) signals, physical uplink control channel (PUCCH) signals, any RS, etc.). The Tx and the Rx may indicate some assistance information to each other. For example, the assistance information may include: Tx pre- compensation capability; PN characteristics indication for Tx and Rx; indication of signals passing through same main local oscillators; indication of any event leading to phase noise inconsistency, etc.

[0080] The access node may determine to perform PN pre- compensation. For example, the access node may determine whether to turn on/off or to adjust the PN pre-compensation and its related parts/elements (e.g. PN estimator, relevant inputs, weights, etc.).

[0081] In an example embodiment, a transmitter may determine to perform PN compensation based, at least partially, on a subcarrier spacing threshold. For example, smaller SCS are more sensitive to PN, and PN pre-compensation may be activated mainly for SCS < 60KHz in FR3 and higher SCS for higher carrier frequencies.

[0082] In an example embodiment, a transmitter may determine to perform PN compensation based, at least partially, on a carrier or allocated bandwidth threshold or a threshold for number of allocated resource block. For example, a larger RB allocation may increase the impact of an uncorrelated part, and at some point PN pre-compensation complexity may not pay off with sufficient performance gain, so PN pre-compensation may be activated for a smaller BW, or in order of local oscillator corner frequency, and deactivated for larger BW, for example greater than a local oscillator corner frequency where uncorrelated PN is dominant, since PN pre-compensation focus mainly on correlated PN.

[0083] In an example embodiment, a transmitter may determine to perform PN compensation based, at least partially, on carrier frequency thresholds. For example, PN pre-compensation may be activated for 10GHz <=fc<= 71 GHz, where PN may be more correlated and these values may be configurable according to a UE indication of its LO or PN characteristics.

[0084] At 710, the access node/Tx may transmit, to the UE/Rx, a PN pre-compensation assistance information request. At 715, the UE/Rx may transmit, to the access node/Tx, the PN pre-compensation assistance information (e.g. PN characteristics, phase noise consistency indication, possible relevant signals, etc.).

[0085] At 720, the access node/Tx may transmit, to the UE/Rx, a DL signal (re)-configuration (e.g. PT-RS configuration, PN post- compensation, PN pre-compensation related indications (e.g. threshold, etc.)). At 725, the UE/Rx may transmit, to the access node/Tx, UL signals (e.g. PUSCH, PUCCH, any RS, etc.).

[0086] At 730, the access node/Tx may determine, based on the received assistance information, which physical channels (e.g. RS, previously correctly decoded data from earlier exchanges, etc.) may be used in the PN estimation or pre-compensation, and may determine whether an earlier PN estimations is relevant to be used in pre-compensation (e.g. satisfying the conditions, reliable estimations, etc.). When the set of conditions are satisfied, the Tx pre-compensation may be performed. [0087] At 735, the access node/Tx may perform new PN estimations.

[0088] At 740, the access node/Tx may perform pre-compensation for the DL PN, for example based on the earlier PN estimation during the received UL channels with PTRS from the same UE (e.g. PUSCH). Additionally or alternatively, the access node/Tx may perform pre-compensation for the DL PN based on a new estimation using at least one of the following: the existing RS (e.g. PT-RS, demodulation reference signal (DMRS), sounding reference signal (SRS), etc.) in UL channels, and/or a reconstructed signal of earlier correctly decoded UL with its received version, and/or any other know or predictable part in the UL signals (e.g. cyclic- prefix, known-tail (KT), unique word, etc.).

[0089] In an example embodiment, in order to perform PN pre- compensation, it may be mandatory to receive at least one signal from a second apparatus so that it can be considered in the PN pre-compensation. For example, the at least one signal may be used or not depending on whether it is relevant (i.e. meets some metric of relevancy). For example, the signal carrying the assistance information may be a potential signal.

[0090] At 745, the access node/Tx may transmit, to the UE/Rx, DL signal(s) with PN pre-compensated, for example based on earlier UL signals and received indication(s). At 750, the access node/Tx may transmit, to the UE/Rx, a PN pre-compensation indication or confirmation. At 755, the UE/Rx may transmit, to the access node/Tx, feedback in response.

[0091] Referring now to FIG. 8, illustrated is a signaling diagram for Tx PN pre-compensation at a UE for UL signals. In other words, the UE may act as the Tx, while the access node may act as the Rx. At 805, the access node/Rx may optionally transmit earlier DL signals to the UE/Tx (e.g. physical downlink shared channel (PDSCH) signals, physical downlink control channel (PDCCH), synchronization signal block (SSB), any RS, etc.). The Tx and the Rx may indicate some assistance information to each other. For example, the assistance information may include: Tx pre-compensation capability, especially by UE in UL; PN characteristics indication for Tx and Rx; indication of channels passing through same main local oscillators; indication of any event leading to phase noise inconsistency, etc.

[0092] At 810, the UE/Tx may transmit, to the access node/Rx, a PN pre-compensation assistance information request or capability reporting. At 815, the access node/Rx may transmit, to the UE/Tx, PN pre-compensation assistance information (e.g. PN characteristics, phase noise consistency indication, relevant signals (e.g. at 825), etc. Relevant signals, such as PDSCH, PDCCH, SSB, etc., may be UE-specific for the UE communicating with the access node, may be UE-specific for another UE, group-specific, cell-specific (e.g. for all UEs in the cell), etc.

[0093] It may be noted that a UE performing PN pre-compensation for UL may also use the signals (e.g. RS) or physical channels (e.g. PDSCH, PDCCH) sent to other UEs, for example if it is indicated by the gNB that they are passing through that same LO(s), which may be the case for time-multiplexed UEs or frequency multiplexed UE on a same band/BWP etc. For example, PDxCH for UE1 and PDxCH for UE2 can be may both be considered in the PN estimation at UE1 for PN pre-compensation. [0094] At 820, the access node/Rx may transmit, to the UE/Tx, a UL signal (re)-configuration (e.g. PT-RS configuration, PN post- compensation, PN pre-compensation related indications (e.g. threshold, etc.)). At 825, the access node/Rx may transmit, to the UE/TX, DL signals (e.g. PDSCH, PDCCH, SSB, any RS, etc.).

[0095] At 830, the UE/Tx may determine, based on the received assistance information, which physical channels (SSB only for UL pre-compensation, and/or RS, previously correctly decoded data from earlier exchanges, etc.) may be used in the PN estimation or pre-compensation, and may determine whether an earlier PN estimations is relevant to be used in pre-compensation (e.g. satisfying the conditions, reliable estimations, etc.). When the set of conditions are satisfied, the Tx pre-compensation may be performed.

[0096] At 835, the UE/Tx may perform new PN estimations.

[0097] At 840, the UE may perform pre-compensation for the UL PN, for example based on the earlier PN estimation during the received DL channels with PTRS from the same gNB (e.g. PDSCH). Additionally or alternatively, the UE may perform pre-compensation for the UL PN based on a new estimation using received RS and/or correctly decoded data at least in on one of the following: periodic SSB, available RS signals (not limited to PT-RS, DMRS, CSI RS), or the reconstructed Tx signal using the correctly decoded data in previous DL channels with its received version (e.g. PDCCH, PDSCH, etc.).

[0098] At 845, the UE/Tx may transmit, to the access node/Rx, UL signal(s) with PN pre-compensated based on earlier DL signals and received indication(s). At 850, the UE/Tx may transmit, to the access node/Rx, a PN pre-compensation indication or confirmation. At 855, the access node/Rx may transmit, to the UE/Tx, feedback in response.

[0099] In an example embodiment, the main factors needed to determine (1) the possibility/necessity of Tx PN pre-compensation (e.g. based on assistance information), and (2) the relevant previous PN estimations and/or received signals, even those without PTRS (possibly for new estimations) or those for other UE, at 730/830, may include one or more of the following. For example, Tx PN pre-compensation may be used at non-negligible correlated PN level(s) (i.e. depending on PN characteristics or PN level generated for the used LOs at Tx, Rx, or both). For example, signals passing through common LOs paths for Tx/Rx may be used: signal(s) in the opposite link used by the same main LO(s) as the new Rx signal(s) that may be received before Tx PN pre- compensation. The signals from the same main LO may be referring to either exactly the output of the same LO for Tx/Rx paths at each node (e.g., TDD), or to those generated by a common LO with a deterministic frequency multiplier or shift (e.g., FDD). For example, the PN estimations may be based on the same Tx-Rx LOs pairs. For example, phase noise consistency may be used: the Tx may determine the previous received signals that maintained a phase noise consistency with the current configured/scheduled transmission. The phase consistency may not be maintained, for example if hardware shut-down is performed during a Tx or Rx sleep mode.

[00100] In an example embodiment, the Tx may indicate to the Rx, implicitly or explicitly at 750/850, if pre-compensation is not performed, or could be performed, or is performed. This indication may have the technical effect of helping the Rx to adapt accordingly (e.g. change estimation algorithm, deactivate post- compensation, etc.). This indication may have the technical effect of enabling the gNB to adapt PN post-compensation configuration for UL channels (e.g. adapt PTRS density/pattern (possibly to consider residual PN and uncorrelated PN if necessary), activate or choose other parameters for advanced PN post-compensation solution, etc.). This indication may be based on a determination that Tx and Rx pre/post-compensation may be tied to some conditions as indication (e.g. MCS threshold) when they are not activated or not needed. Otherwise, Tx pre- compensation may be performed, or not, depending on the Tx determination and availability of relevant valid signals. This indication may be based on a determination that the activation of the PN pre-compensation may be indicated/requested by defining a threshold related to RF parameter(s), for example if EVM and/or ACLR and/or OOB >= threshold (s), PN pre-compensation may be activated, else it may be assumed that no Tx PN pre-compensation is performed.

[00101] In an example embodiment, without a clear Tx indication, if the PN pre-compensation is performed mainly by the UE in UL (e.g. FIG. 8), the Rx may not reduce its PN post-compensation frequency or choose simple PN estimation algorithm. Note that, in the DL (e.g. FIG. 7), the gNB may adapt/remove PT-RS to control PN post-compensation frequency, if any, according to whether Tx PN pre-compensation is performed. Thus, the UL Rx (i.e. gNB) may not lower its computational complexity, and may post-compensate the residual PN from Tx pre-compensation and the uncorrelated PN. The RX post-compensation may be performed assuming a worst case, without Tx PN pre-compensation according to some factors (MCS, PN characteristics indications, carrier frequency, bandwidth and SCS, etc.).

[00102] In an example embodiment, the Tx may perform digital PN pre-compensation using earlier PN estimation(s), at 740/840, if they are determined as relevant, at 730/830, and may possibly perform additional or new PN estimation(s) using relevant received signals even those without PTRS, at 735/835. Note that any PN estimation algorithm relevant to the indicated PN characteristics, like those in Rx post-compensation, may be used. In an example embodiment, relevant inputs to the PN estimator may be determined (i.e. which Rx signal(s) and corresponding Tx signal(s) comprising RS may or may not be relevant). In an example embodiment, phase noise estimation may be performed, which may have the technical effect of improving earlier estimations due to the possibility of a larger number of samples in the PN estimator. For example, the 5G-NR PN estimation uses mainly PT-RS samples only, which may be dedicated for this UE. In an example embodiment, all relevant previous REs including data REs and any existing RSs (e.g. PTRS, DMRS, RS dedicated for this UE or not, etc.) may be used for estimation. In an example embodiment, estimation may be performed based on at least one of the following: a non-predefined symbol (i.e. correctly decoded data in previous signal(s), cyclic prefix (CP), etc.) and explicit reference signal (not limited to PTRS) or pre-defined/known symbol (e.g. KT, unique word (UW), etc.). In other words, the Tx node may reconstruct or store earlier received signal(s) from the other node, and then use it with its corresponding received signal(s) observation. In other words, the previously observed PN may be used for the currently received signals. In an example embodiment, the PN pre-compensation may use more than one of the earlier PN estimations and process them, for example by averaging, grouping, adaptive filtering, interpolating, using Al models or predicting models, etc. In an example embodiment, the earlier estimations at the Tx may be weighted or discarded according to their reliability and/or expected accuracy, which may be affected by one or more of the following: number of PTRS samples/density used in the estimator, SNR, RSRP, CQI, earlier successful data decoding, etc. For example, if there are only a few PTRS samples or poor SNR for earlier estimations, one may consider those as too unreliable (e.g., below some reliability threshold or expected accuracy).

[00103] In an example embodiment, the Rx may indicate or report, for example at 755/855, an indicator about the PN level or the Tx pre-compensation accuracy or efficiency. This report may be an implicit indication to request Tx pre-compensation activation when possible, or its adaptation.

[00104] In an example embodiment, the related signaling and reports in 710/715/720/750/755 and 810/815/820/850/855 may be transmitted/received using one or more of the following: RRC, MAC- CE and downlink or uplink control information, depending on the direction of the transmission.

[00105] Example embodiments of the present disclosure may co-exist with or enhance solutions such as Zahedi-Ghasabeh et al., where a PN pre-compensation based on a hardware feedback path is considered. A joint effort between example embodiments of the present disclosure and other solutions may have the technical effect of achieving better Tx PN pre-compensation, or better with only uncorrelated PN noise floor as residual part at Rx. [00106] Example embodiments of the present disclosure may be adaptive and may consider the overall Tx and Rx PN, and not only Tx PN.

[00107] Example embodiments of the present disclosure may be used at FR3 and FR2, and higher frequencies, especially for low complexity/cost Rx and Tx devices (e.g. UE), for example for dominant correlated PN and/or for certain MCS order(s).

[00108] Example embodiments of the present disclosure may be used at sub-THz (or higher frequencies) to compensate only the correlated PN part at Tx. A technical effect of example embodiments of the present disclosure may be to allow better estimation of the uncorrelated PN at Rx (i.e. decoupling PN estimation/compensation, for example correlated PN component compensated at Tx mainly and uncorrelated at Rx.

[00109] Example embodiments of the present disclosure may be used with any waveform and any UL or DL physical channels, even those without any PTRS (e.g. PDSCH, PDCCH, PUSCH,PUCCH).

[00110] A technical effect of example embodiments of the present disclosure may be to enhance coverage for all physical channels, and especially for PTRS-less channels (e.g. PDCCH, PUCCH), by pre- compensating PN at Tx without additional PTRS overhead.

[00111] A technical effect of example embodiments of the present disclosure may be to enhance coverage/energy efficiency and spectral efficiency, since PN pre-compensation may enhance the signal quality (e.g. EVM, OOB, ACLR) and thus the SNR observed at Rx. A technical effect of example embodiments of the present disclosure may be to allow use of a higher modulation order and achieve higher spectral efficiency.

[00112] A technical effect of example embodiments of the present disclosure may be to allow reduction of the interference to adjacent users (less OOB, less ACLR) compared to the low-quality RF signal without Tx pre-compensation.

[00113] A technical effect of example embodiments of the present disclosure may be to allow enhancement of the energy efficiency of the system (due to enable operating at lower SNR, possible smaller OBO for PA to satisfy RF requirements with these reduced distortions, etc.).

[00114] A technical effect of example embodiments of the present disclosure may be to allow reduction or avoidance of PTRS overhead when the PN pre-compensation is valid with a good accuracy PN that is mainly sufficiently correlated. A technical effect of example embodiments of the present disclosure may be to allow selection of PT-RS patterns more suitable for other PN components if any and necessary (uncorrelated). A technical effect of example embodiments of the present disclosure may be to allow for enhancement of coverage for all physical channels due to lower PN after pre-compensation and possible smaller coding rate, if PTRS overhead is lowered while maintaining/enhancing the PN estimation/compensation accuracy.

[00115] A technical effect of example embodiments of the present disclosure may be to allow reduction of Rx computational complexity by reducing the frequency of PN estimation/compensation or by adopting simpler estimation algorithms to compensate only residual PN if necessary. [00116] A technical effect of example embodiments of the present disclosure may be to enable PN post-compensation at Rx to be removed or relaxed depending on different factors (e.g. MCS, residual and uncorrelated PN level, etc.), which is an important advantage for UE complexity in DL and UL coverage enhancement.

[00117] A technical effect of example embodiments of the present disclosure may be to reduce estimation quality impact.

[00118] A technical effect of example embodiments of the present disclosure may be to avoid impact based on hardware imperfection(s), self-interference from Tx path, and/or other possible RF impairments, for example in comparison to Tx PN pre- compensation based on hardware RF loopback.

[00119] FIG. 9 illustrates the potential steps of an example method 900. The example method 900 may include: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus, 910; receiving, from the second apparatus, at least one signal, 920; and performing the phase noise pre-compensation on the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal, 930. The first apparatus may be/comprise a TX point/TX. The second apparatus may be/comprise a RX point/RX. The example method 900 may be performed, for example, with a transmitter, for example a UE transmitting UL signals, or a base station, gNB, access node, or network node transmitting DL signals. The transmitter may also be configured to receive signals.

[00120] The at least one received signal may be, for example, a signal as at 705 (e.g. earlier UL signals: PUSCH, PUCCH, RS, etc.) and/or 725 (e.g. UL signals: PUSCH, PUCCH, RS, etc.) of FIG. 7, and/or 805 (e.g. earlier DL signals: PDSCH, PDCCH, SSB, RS, etc.) and/or 825 (e.g. earlier DL signals: PDSCH, PDCCH, SSB, RS, etc.) of FIG. 8. At least one of a signal as at 705 or a signal as at 725 may be needed to perform PN pre-compensation in the example of FIG. 7. At least one of a signal as at 805 or a signal as at 825 may be needed to perform PN pre-compensation in the example of FIG. 8.

[00121] Additionally or alternatively, the at least one received signal may carry assistance information as data.

[00122] In an example embodiment, the example method 900 may further comprise receiving, from the second apparatus, an indication of assistance information; however, this may be optional. The "indication" may be the information itself, or some indication related to PN pre-compensation. For example, if we consider a SISO (one LO at Tx and one at Rx) communication and TDD communication with UL/DL on a same frequency multiplexed in time, the Tx, especially if it is a UE, may perform PN pre-compensation using the relevant signal(s) (e.g. the at least one received signal) from the other apparatus, since they are expected to be from the same LOs and UE knows its PN characteristics. In another example embodiment, even in the above example, assistance information may be used to avoid using DL signals where phase noise consistency or phase continuity is not maintained, for example if it is transparent to the UE. In another example embodiment, assistance information may be needed in case of FDD, or multiple antennas, DL PN pre-compensation, etc. [00123] FIG. 10 illustrates the potential steps of an example method 1000. The example method 1000 may include: transmitting, with a first apparatus to a second apparatus, at least one signal, 1010; and receiving, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre- compensated based, at least partially, on the at least one transmitted signal, 1020. The first apparatus may be/comprise a RX point/RX. The second apparatus may be/comprise a TX point/TX. The example method 1200 may be performed, for example, with a receiver, for example a UE receiving DL signals, or a base station, gNB, access node, or network node receiving UL signals. The receiver may also be configured to transmit signals.

[00124] The at least one transmitted signal may be, for example, a signal as at 705 (e.g. earlier UL signals: PUSCH, PUCCH, RS, etc.) and/or 725 (e.g. UL signals: PUSCH, PUCCH, RS, etc.) of FIG.

7, and/or 805 (e.g. earlier DL signals: PDSCH, PDCCH, SSB, RS, etc.) and/or 825 (e.g. earlier DL signals: PDSCH, PDCCH, SSB, RS, etc.) of FIG. 8. At least one of a signal as at 705 or a signal as at 725 may be needed to perform PN pre-compensation in the example of FIG. 7. At least one of a signal as at 805 or a signal as at 825 may be needed to perform PN pre-compensation in the example of FIG. 8.

[00125] In an example embodiment, the example method 1000 may further comprise transmitting, to the second apparatus, an indication of assistance information; however, this may be optional. The at least one signal may optionally be pre- compensated based on the assistance information. [00126] In accordance with one example embodiment, a first apparatus may comprise: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: determine to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receive, from the second apparatus, at least one signal; and perform the phase noise pre- compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00127] The example first apparatus may be further configured to: receive, from the second apparatus, a request to perform the phase noise pre-compensation.

[00128] Determining to perform the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus may be based, at least partially, on at least one of: a modulation and coding scheme threshold, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, an availability of signals for the phase noise pre- compensation, an error vector magnitude, a determination that the error vector magnitude is larger than or equal to a first threshold, an out-of-band radiation, a determination that the out- of-band radiation is larger than or equal to a second threshold, an adjacent channel leakage, or a determination that the adjacent channel leakage ratio is larger than or equal to a third threshold. [00129] The example first apparatus may be further configured to: transmit, to the second apparatus, a request for assistance information.

[00130] The example first apparatus may be further configured to: receive, from the second apparatus, the assistance information in response to the request.

[00131] The example first apparatus may be further configured to: transmit, to the second apparatus, a phase noise pre-compensation indication; and receive, from the second apparatus, feedback in response.

[00132] The phase noise pre-compensation indication may be configured to indicate at least one of: a time duration, or a periodicity for the phase noise pre-compensation.

[00133] The received feedback may comprise at least one of: an indication of an accuracy of the phase noise pre-compensation, an indication of an observed phase noise with respect to the at least one phase noise pre-compensated signal, a request to activate or adapt the phase noise pre-compensation, or an indication of a phase noise level.

[00134] The example first apparatus may be further configured to: determine at least one of: one or more relevant phase noise estimations, or one or more relevant signals, wherein the phase noise pre-compensation performed on the at least one signal to be transmitted to the second apparatus may be further based on the at least one of: the one or more relevant phase noise estimations, or the one or more relevant signals. [00135] The one or more relevant phase noise estimations may comprise at least one of: a phase noise estimation at the first apparatus, or a phase noise estimation at the second apparatus.

[00136] The one or more relevant phase noise estimations may comprise one or more phase noise estimations that satisfy at least one condition of reliability, wherein the one or more relevant phase noise estimations may comprise at least one of: one or more pre-existing phase noise estimations, or one or more new phase noise estimations determined based, at least partially, on the one or more relevant signals.

[00137] The at least one of the one or more relevant phase noise estimations or the one or more relevant signals may be determined based, at least partially, on phase noise consistency.

[00138] The one or more relevant phase noise estimations may comprise, at least, a phase noise estimation weighted based on at least one of: a number of available phase tracking reference signal samples, a signal to noise ratio, a reference signal received power, a channel quality indicator, or earlier successful data decoding.

[00139] The one or more relevant signals may comprise the at least one received signal or a corresponding signal to be transmitted to the second apparatus.

[00140] The one or more relevant signals may comprise at least one of: a reconstructed signal received from the second apparatus, a stored received signal, or a received signal corresponding to the reconstructed received signal. It may be noted that, at the first apparatus performing PN pre-compensation, the construction/generation of the initially modulated signal may be based on the decoded symbols, or bits for the corresponding received signal from the second apparatus.

[00141] The one or more relevant signals may be determined based, at least partially, on assistance information.

[00142] The phase noise pre-compensation of the at least one signal may be further performed based on assistance information.

[00143] The assistance information may comprise an indication of at least one of: a phase noise characteristic, a phase noise consistency indication, a possibly relevant signal, a pre- compensation capability, an indication of an event configured to cause phase noise inconsistency, an indication of a channel passing through a main local oscillator at the second apparatus, at least one modulation and coding scheme to which the pre-compensation is configured to be applied, at least one subcarrier spacing to which the pre-compensation is configured to be applied, a maximum tolerable phase noise level, a characteristic of a local oscillator, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, or a maximum tolerable radio frequency requirement level.

[00144] The first apparatus may comprise an access node.

[00145] The example first apparatus may be further configured to: transmit, to the second apparatus, the at least one phase noise pre-compensated signal, wherein the at least one phase noise pre- compensated signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

[00146] The at least one received signal may comprise at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

[00147] The example first apparatus may be further configured to: determine one or more relevant phase noise estimations, wherein the one or more relevant phase noise estimations may comprise at least one of: a phase noise estimation during reception of a phase tracking reference signal from the second apparatus, a phase noise estimation during reception of a reference signal, or a phase noise estimation using a reconstructed signal of a correctly decoded uplink signal with its received version.

[00148] The example first apparatus may be further configured to: transmit, to the second apparatus, a signal configuration, wherein the signal configuration may comprise, at least, one or more phase noise pre-compensation related indications.

[00149] The signal configuration may further comprise at least one of: a phase tracking reference signal configuration, or a phase noise post-compensation configuration.

[00150] The first apparatus may comprise a user equipment.

[00151] The example first apparatus may be further configured to: transmit, to the second apparatus, the at least one phase noise pre-compensated signal, wherein the at least one phase noise pre- compensated signal may comprise at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal. [00152] The at least one received signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

[00153] The example first apparatus may be further configured to: determine one or more relevant phase noise estimations, wherein the one or more relevant phase noise estimations may comprise at least one of: a phase noise estimation during reception of a phase tracking reference signal from the second apparatus, a phase noise estimation during reception of a periodic synchronization signal block, a phase noise estimation during reception of a reference signal, or a phase noise estimation using a reconstructed downlink signal of a correctly decoded downlink signal with its received version.

[00154] In accordance with one aspect, an example method may be provided comprising: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receiving, from the second apparatus, at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00155] The example method may further comprise: receiving, from the second apparatus, a request to perform the phase noise pre- compensation.

[00156] The determining to perform the phase noise pre- compensation of the at least one signal to be transmitted to the second apparatus may be based, at least partially, on at least one of: a modulation and coding scheme threshold, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, an availability of signals for the phase noise pre- compensation, an error vector magnitude, a determination that the error vector magnitude is larger than or equal to a first threshold, an out-of-band radiation, a determination that the out- of-band radiation is larger than or equal to a second threshold, an adjacent channel leakage, or a determination that the adjacent channel leakage ratio is larger than or equal to a third threshold.

[00157] The example method may further comprise: transmitting, to the second apparatus, a request for assistance information.

[00158] The example method may further comprise: receiving, from the second apparatus, the assistance information in response to the request.

[00159] The example method may further comprise: transmitting, to the second apparatus, a phase noise pre-compensation indication; and receiving, from the second apparatus, feedback in response.

[00160] The phase noise pre-compensation indication may be configured to indicate at least one of: a time duration, or a periodicity for the phase noise pre-compensation.

[00161] The received feedback may comprise at least one of: an indication of an accuracy of the phase noise pre-compensation, an indication of an observed phase noise with respect to the at least one phase noise pre-compensated signal, a request to activate or adapt the phase noise pre-compensation, or an indication of a phase noise level.

[00162] The example method may further comprise: determining at least one of: one or more relevant phase noise estimations, or one or more relevant signals, wherein the phase noise pre-compensation performed on the at least one signal to be transmitted to the second apparatus may be further based on the at least one of: the one or more relevant phase noise estimations, or the one or more relevant signals.

[00163] The one or more relevant phase noise estimations may comprise at least one of: a phase noise estimation at the first apparatus, or a phase noise estimation at the second apparatus.

[00164] The one or more relevant phase noise estimations may comprise one or more phase noise estimations that satisfy at least one condition of reliability, wherein the one or more relevant phase noise estimations may comprise at least one of: one or more pre-existing phase noise estimations, or one or more new phase noise estimations determined based, at least partially, on the one or more relevant signals.

[00165] The at least one of the one or more relevant phase noise estimations or the one or more relevant signals may be determined based, at least partially, on phase noise consistency.

[00166] The one or more relevant phase noise estimations may comprise, at least, a phase noise estimation weighted based on at least one of: a number of available phase tracking reference signal samples, a signal to noise ratio, a reference signal received power, a channel quality indicator, or earlier successful data decoding.

[00167] The one or more relevant signals may comprise the at least one received signal or a corresponding signal to be transmitted to the second apparatus.

[00168] The one or more relevant signals may comprise at least one of: a reconstructed signal received from the second apparatus, a stored received signal, or a received signal corresponding to the reconstructed received signal.

[00169] The one or more relevant signals may be determined based, at least partially, on assistance information.

[00170] The phase noise pre-compensation of the at least one signal may be further performed based on assistance information.

[00171] The assistance information may comprise an indication of at least one of: a phase noise characteristic, a phase noise consistency indication, a possibly relevant signal, a pre- compensation capability, an indication of an event configured to cause phase noise inconsistency, an indication of a channel passing through a main local oscillator at the second apparatus, at least one modulation and coding scheme to which the pre-compensation is configured to be applied, at least one subcarrier spacing to which the pre-compensation is configured to be applied, a maximum tolerable phase noise level, a characteristic of a local oscillator, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, or a maximum tolerable radio frequency requirement level. [00172] The first apparatus may comprise an access node.

[00173] The example method may further comprise: transmitting, to the second apparatus, the at least one phase noise pre-compensated signal, wherein the at least one phase noise pre-compensated signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

[00174] The at least one received signal comprises at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

[00175] The example method may further comprise: determining one or more relevant phase noise estimations, wherein the one or more relevant phase noise estimations may comprise at least one of: a phase noise estimation during reception of a phase tracking reference signal from the second apparatus, a phase noise estimation during reception of a reference signal, or a phase noise estimation using a reconstructed signal of a correctly decoded uplink signal with its received version.

[00176] The example method may further comprise: transmitting, to the second apparatus, a signal configuration, wherein the signal configuration may comprise, at least, one or more phase noise pre- compensation related indications.

[00177] The signal configuration may further comprise at least one of: a phase tracking reference signal configuration, or a phase noise post-compensation configuration.

[00178] The first apparatus may comprise a user equipment. [00179] The example method may further comprise: transmitting, to the second apparatus, the at least one phase noise pre-compensated signal, wherein the at least one phase noise pre-compensated signal may comprise at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

[00180] The at least one received signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

[00181] The example method may further comprise: determine one or more relevant phase noise estimations, wherein the one or more relevant phase noise estimations may comprise at least one of: a phase noise estimation during reception of a phase tracking reference signal from the second apparatus, a phase noise estimation during reception of a periodic synchronization signal block, a phase noise estimation during reception of a reference signal, or a phase noise estimation using a reconstructed downlink signal of a correctly decoded downlink signal with its received version.

[00182] In accordance with one example embodiment, a first apparatus may comprise: circuitry configured to perform: determining to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; circuitry configured to perform: receiving, from the second apparatus, at least one signal; and circuitry configured to perform: the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00183] In accordance with one example embodiment, a first apparatus may comprise: processing circuitry; memory circuitry including computer program code, the memory circuitry and the computer program code configured to, with the processing circuitry, enable the apparatus to: determine to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receive, from the second apparatus, at least one signal; and perform the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00184] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit (s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor (s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation." This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[00185] In accordance with one example embodiment, an apparatus may comprise means for: determining to perform phase noise pre- compensation of at least one signal to be transmitted to a second apparatus; receiving, from the second apparatus, at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00186] In accordance with one example embodiment, an apparatus may comprise means for performing a method according to any of the foregoing.

[00187] A processor, memory, and/or example algorithms (which may be encoded as instructions, program, or code) may be provided as example means for providing or causing performance of operation.

[00188] In accordance with one example embodiment, a non- transitory computer-readable medium comprising instructions stored thereon which, when executed with at least one processor, cause the at least one processor to: determine, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; cause receiving, from the second apparatus, of at least one signal; and perform the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00189] In accordance with one example embodiment, a non- transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: determining, with a first apparatus, to perform phase noise pre- compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00190] In accordance with another example embodiment, a non- transitory program storage device readable by a machine may be provided, tangibly embodying instructions executable by the machine for performing operations, the operations comprising: determining, with a first apparatus, to perform phase noise pre- compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00191] In accordance with another example embodiment, a non- transitory computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00192] A computer implemented system comprising: at least one processor and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the system at least to perform: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00193] A computer implemented system comprising: means for determining, with a first apparatus, to perform phase noise pre- compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and means for performing the phase noise pre- compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00194] In accordance with another example embodiment, a computer program may comprise instructions stored thereon for performing at least the following: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

[00195] In accordance with one example embodiment, a first apparatus may comprise: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit, to a second apparatus, at least one signal; and receive, from the second apparatus, at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00196] The example first apparatus may be further configured to: transmit, to the second apparatus, a request to perform the phase noise pre-compensation.

[00197] The request to perform the phase noise pre-compensation may be transmitted in response to at least one of: a power-saving decision, a signal-to-noise ratio degradation, a modulation and coding scheme, a subcarrier spacing, an allocated bandwidth, a carrier frequency modification, a number of failed decoding attempts, or a phase tracking reference signal configuration.

[00198] The example first apparatus may be further configured to: receive, from the second apparatus, a request for assistance information; and transmit the assistance information in response to the request. [00199] The assistance information may comprise an indication of at least one of: a phase noise characteristic, a phase noise consistency indication, a possibly relevant signal, a pre- compensation capability, an indication of an event configured to cause phase noise inconsistency, an indication of a channel passing through a main local oscillator at the first apparatus, at least one modulation and coding scheme to which the pre-compensation is configured to be applied, at least one subcarrier spacing to which the pre-compensation is configured to be applied, a maximum tolerable phase noise level, a characteristic of a local oscillator, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, or a maximum tolerable radio frequency requirement level.

[00200] The example first apparatus may be further configured to: receive, from the second apparatus, a phase noise pre-compensation indication; and transmit, to the second apparatus, feedback in response.

[00201] The phase noise pre-compensation indication may be configured to indicate at least one of: a time duration, or a periodicity for phase noise pre-compensation of the at least one received signal.

[00202] The transmitted feedback may comprise at least one of: an indication of an accuracy of the phase noise pre-compensation, an indication of an observed phase noise with respect to the at least one received signal, a request to activate or adapt phase noise pre-compensation, or an indication of a phase noise level. [00203] The example first apparatus may be further configured to: perform, in response to the phase noise pre-compensation indication, at least one of: phase tracking reference signal density adaptation, phase tracking reference signal pattern adaptation, or selection of at least one parameter for phase noise post-compensation in response to the phase noise pre-compensation indication.

[00204] The first apparatus may comprise an access node.

[00205] The at least one transmitted signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

[00206] The at least one received signal may comprise at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

[00207] The first apparatus may comprise a user equipment.

[00208] The at least one transmitted signal may comprise at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

[00209] The at least one received signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal. [00210] The example first apparatus may be further configured to: receive, from the second apparatus, a signal configuration, wherein the signal configuration may comprise, at least, one or more phase noise pre-compensation related indications.

[00211] The signal configuration may further comprise at least one of: a phase tracking reference signal configuration, or a phase noise post-compensation configuration.

[00212] In accordance with one aspect, an example method may be provided comprising: transmitting, with a first apparatus to a second apparatus, at least one signal; and receiving, from the second apparatus, at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00213] The example method may further comprise: transmitting, to the second apparatus, a request to perform the phase noise pre- compensation.

[00214] The request to perform the phase noise pre-compensation may be transmitted in response to at least one of: a power-saving decision, a signal-to-noise ratio degradation, a modulation and coding scheme, a subcarrier spacing, an allocated bandwidth, a carrier frequency modification, a number of failed decoding attempts, or a phase tracking reference signal configuration.

[00215] The example method may further comprise: receiving, from the second apparatus, a request for the assistance information; and transmitting the assistance information in response to the request. [00216] The assistance information may comprise an indication of at least one of: a phase noise characteristic, a phase noise consistency indication, a possibly relevant signal, a pre- compensation capability, an indication of an event configured to cause phase noise inconsistency, an indication of a channel passing through a main local oscillator at the first apparatus, at least one modulation and coding scheme to which the pre-compensation is configured to be applied, at least one subcarrier spacing to which the pre-compensation is configured to be applied, a maximum tolerable phase noise level, a characteristic of a local oscillator, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, or a maximum tolerable radio frequency requirement level.

[00217] The example method may further comprise: receiving, from the second apparatus, a phase noise pre-compensation indication; and transmitting, to the second apparatus, feedback in response.

[00218] The phase noise pre-compensation indication may be configured to indicate at least one of: a time duration, or a periodicity for phase noise pre-compensation of the at least one received signal.

[00219] The transmitted feedback may comprise at least one of: an indication of an accuracy of the phase noise pre-compensation, an indication of an observed phase noise with respect to the at least one received signal, a request to activate or adapt phase noise pre-compensation, or an indication of a phase noise level.

[00220] The example method may further comprise: performing, in response to the phase noise pre-compensation indication, at least one of: phase tracking reference signal density adaptation, phase tracking reference signal pattern adaptation, or selection of at least one parameter for phase noise post-compensation in response to the phase noise pre-compensation indication.

[00221] The first apparatus may comprise an access node.

[00222] The at least one transmitted signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

[00223] The at least one received signal may comprise at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

[00224] The first apparatus may comprise a user equipment.

[00225] The at least one transmitted signal may comprise at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

[00226] The at least one received signal may comprise at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

[00227] The example method may further comprise: receiving, from the second apparatus, a signal configuration, wherein the signal configuration may comprise, at least, one or more phase noise pre- compensation related indications. [00228] The signal configuration may further comprise at least one of: a phase tracking reference signal configuration, or a phase noise post-compensation configuration.

[00229] In accordance with one example embodiment, a first apparatus may comprise: circuitry configured to perform: transmitting, to a second apparatus, at least one signal; and circuitry configured to perform: receiving, from the second apparatus, at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00230] In accordance with one example embodiment, an apparatus may comprise: processing circuitry; memory circuitry including computer program code, the memory circuitry and the computer program code configured to, with the processing circuitry, enable the apparatus to: transmit, to a second apparatus, at least one signal; and receive, from the second apparatus, at least one signal, wherein the at least one signal may be phase noise pre- compensated based, at least partially, on the at least one transmitted signal .

[00231] In accordance with one example embodiment, an apparatus may comprise means for:transmitting, to a second apparatus, at least one signal; and receiving, from the second apparatus, at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00232] In accordance with one example embodiment, an apparatus may comprise means for performing a method according to any of the foregoing. [00233] In accordance with one example embodiment, a non- transitory computer-readable medium comprising instructions stored thereon which, when executed with at least one processor, cause the at least one processor to: cause transmitting, with a first apparatus to a second apparatus, of at least one signal; and cause receiving, from the second apparatus, of at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00234] In accordance with one example embodiment, a non- transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00235] In accordance with another example embodiment, a non- transitory program storage device readable by a machine may be provided, tangibly embodying instructions executable by the machine for performing operations, the operations comprising: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00236] In accordance with another example embodiment, a non- transitory computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00237] A computer implemented system comprising: at least one processor and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the system at least to perform: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal may be phase noise pre- compensated based, at least partially, on the at least one transmitted signal.

[00238] A computer implemented system comprising: means for causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and means for causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

[00239] In accordance with another example embodiment, a computer program may comprise instructions stored thereon for performing at least the following: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal may be phase noise pre-compensated based, at least partially, on the at least one transmitted signal. [00240] The term "non-transitory, " as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[00241] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modification and variances which fall within the scope of the appended claims.

Claims

CLAIMS What is claimed is:

1. A first apparatus comprising: at least one processor; and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: determine to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receive, from the second apparatus, at least one signal; and perform the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

2. The first apparatus of claim 1, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: receive, from the second apparatus, a request to perform the phase noise pre-compensation.

3. The first apparatus of claim 1 or 2, wherein determining to perform the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus is based, at least partially, on at least one of: a modulation and coding scheme threshold, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, an availability of signals for the phase noise pre- compensation, an error vector magnitude, a determination that the error vector magnitude is larger than or equal to a first threshold, an out-of-band radiation, a determination that the out-of-band radiation is larger than or equal to a second threshold, an adjacent channel leakage, or a determination that the adjacent channel leakage ratio is larger than or equal to a third threshold.

4. The first apparatus of any of claims 1 through 3, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: transmit, to the second apparatus, a request for assistance information.

5. The first apparatus of claim 4, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: receive, from the second apparatus, the assistance information in response to the request.

6. The first apparatus of any of claims 1 through 5, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: transmit, to the second apparatus, a phase noise pre- compensation indication; and receive, from the second apparatus, feedback in response.

7. The first apparatus of claim 6, wherein the phase noise pre-compensation indication is configured to indicate at least one of: a time duration, or a periodicity for the phase noise pre-compensation.

8. The first apparatus of claim 6 or 7, wherein the received feedback comprises at least one of: an indication of an accuracy of the phase noise pre- compensation, an indication of an observed phase noise with respect to the at least one phase noise pre-compensated signal, a request to activate or adapt the phase noise pre- compensation, or an indication of a phase noise level.

9. The first apparatus of any of claims 1 through 8, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: determine at least one of: one or more relevant phase noise estimations, or one or more relevant signals, wherein the phase noise pre-compensation performed on the at least one signal to be transmitted to the second apparatus is further based on the at least one of: the one or more relevant phase noise estimations, or the one or more relevant signals.

10. The first apparatus of claim 9, wherein the one or more relevant phase noise estimations comprises at least one of: a phase noise estimation at the first apparatus, or a phase noise estimation at the second apparatus.

11. The first apparatus of claim 9 or 10, wherein the one or more relevant phase noise estimations comprises one or more phase noise estimations that satisfy at least one condition of reliability, wherein the one or more relevant phase noise estimations comprise at least one of: one or more pre-existing phase noise estimations, or one or more new phase noise estimations determined based, at least partially, on the one or more relevant signals.

12. The first apparatus of any of claims 9 through 11, wherein the at least one of the one or more relevant phase noise estimations or the one or more relevant signals is determined based, at least partially, on phase noise consistency.

13. The first apparatus of any of claims 9 through 12, wherein the one or more relevant phase noise estimations comprises, at least, a phase noise estimation weighted based on at least one of: a number of available phase tracking reference signal samples, a signal to noise ratio, a reference signal received power, a channel quality indicator, or earlier successful data decoding.

14. The first apparatus of any of claims 9 through 13, wherein the one or more relevant signals comprises the at least one received signal or a corresponding signal to be transmitted to the second apparatus.

15. The first apparatus of any of claims 9 through 14, wherein the one or more relevant signals comprises at least one of: a reconstructed signal received from the second apparatus, a stored received signal, or a received signal corresponding to the reconstructed received signal.

16. The first apparatus of any of claims 9 through 15, wherein the one or more relevant signals is determined based, at least partially, on assistance information.

17. The first apparatus of any of claims 1 through 16, wherein the phase noise pre-compensation of the at least one signal is further performed based on assistance information.

18. The first apparatus of claim 17, wherein the assistance information comprises an indication of at least one of: a phase noise characteristic, a phase noise consistency indication, a possibly relevant signal, a pre-compensation capability, an indication of an event configured to cause phase noise inconsistency, an indication of a channel passing through a main local oscillator at the second apparatus, at least one modulation and coding scheme to which the pre-compensation is configured to be applied, at least one subcarrier spacing to which the pre- compensation is configured to be applied, a maximum tolerable phase noise level, a characteristic of a local oscillator, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, or a maximum tolerable radio frequency requirement level.

19. The first apparatus of any of claims 1 through 18, wherein the first apparatus comprises an access node.

20. The first apparatus of claim 19, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: transmit, to the second apparatus, the at least one phase noise pre-compensated signal, wherein the at least one phase noise pre-compensated signal comprises at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

21. The first apparatus of claim 19 or 20, wherein the at least one received signal comprises at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

22. The first apparatus of any of claims 19 through 21, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: determine one or more relevant phase noise estimations, wherein the one or more relevant phase noise estimations comprise at least one of: a phase noise estimation during reception of a phase tracking reference signal from the second apparatus, a phase noise estimation during reception of a reference signal, or a phase noise estimation using a reconstructed signal of a correctly decoded uplink signal with its received version.

23. The first apparatus of any of claims 19 through 22, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: transmit, to the second apparatus, a signal configuration, wherein the signal configuration comprises, at least, one or more phase noise pre- compensation related indications.

24. The first apparatus of claim 23, wherein the signal configuration further comprises at least one of: a phase tracking reference signal configuration, or a phase noise post-compensation configuration.

25. The first apparatus of any of claims 1 through 19, wherein the first apparatus comprises a user equipment.

26. The first apparatus of claim 25, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: transmit, to the second apparatus, the at least one phase noise pre-compensated signal, wherein the at least one phase noise pre-compensated signal comprises at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

27. The first apparatus of claim 25 or 26, wherein the at least one received signal comprises at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

28. The first apparatus of any of claims 25 through 27, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: determine one or more relevant phase noise estimations, wherein the one or more relevant phase noise estimations comprise at least one of: a phase noise estimation during reception of a phase tracking reference signal from the second apparatus, a phase noise estimation during reception of a periodic synchronization signal block, a phase noise estimation during reception of a reference signal, or a phase noise estimation using a reconstructed downlink signal of a correctly decoded downlink signal with its received version.

29. A method comprising: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receiving, from the second apparatus, at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

30. A first apparatus comprising means for: determining to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; receiving, from the second apparatus, at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

31. A non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

32. A computer program comprising instructions stored thereon for performing at least the following: determining, with a first apparatus, to perform phase noise pre-compensation of at least one signal to be transmitted to a second apparatus; causing receiving, from the second apparatus, of at least one signal; and performing the phase noise pre-compensation of the at least one signal to be transmitted to the second apparatus based, at least partially, on the at least one received signal.

33. A first apparatus comprising: at least one processor; and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: transmit, to a second apparatus, at least one signal; and receive, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal and.

34. The first apparatus of claim 33, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: transmit, to the second apparatus, a request to perform the phase noise pre-compensation.

35. The first apparatus 34, wherein the request to perform the phase noise pre-compensation is transmitted in response to at least one of: a power-saving decision, a signal-to-noise ratio degradation, a modulation and coding scheme, a subcarrier spacing, an allocated bandwidth, a carrier frequency modification, a number of failed decoding attempts, or a phase tracking reference signal configuration.

36. The first apparatus of any of claims 33 through 35, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: receive, from the second apparatus, a request for assistance information; and transmit the assistance information in response to the request.

37. The first apparatus of claim 36, wherein the assistance information comprises an indication of at least one of: a phase noise characteristic, a phase noise consistency indication, a possibly relevant signal, a pre-compensation capability, an indication of an event configured to cause phase noise inconsistency, an indication of a channel passing through a main local oscillator at the first apparatus, at least one modulation and coding scheme to which the pre-compensation is configured to be applied, at least one subcarrier spacing to which the pre- compensation is configured to be applied, a maximum tolerable phase noise level, a characteristic of a local oscillator, a subcarrier spacing threshold, an allocated bandwidth threshold, a threshold for a number of allocated resource blocks, a carrier frequency threshold, or a maximum tolerable radio frequency requirement level.

38. The first apparatus of any of claims 33 through 37, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: receive, from the second apparatus, a phase noise pre- compensation indication; and transmit, to the second apparatus, feedback in response.

39. The first apparatus of claim 38, wherein the phase noise pre-compensation indication is configured to indicate at least one of: a time duration, or a periodicity for phase noise pre-compensation of the at least one received signal.

40. The first apparatus of 38 or 39, wherein the transmitted feedback comprises at least one of: an indication of an accuracy of the phase noise pre- compensation, an indication of an observed phase noise with respect to the at least one received signal, a request to activate or adapt phase noise pre- compensation, or an indication of a phase noise level.

41. The first apparatus of any of claims 38 through 40, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the first apparatus to: perform, in response to the phase noise pre-compensation indication, at least one of: phase tracking reference signal density adaptation, phase tracking reference signal pattern adaptation, or selection of at least one parameter for phase noise post-compensation in response to the phase noise pre-compensation indication.

42. The first apparatus of any of claims 33 through 41, wherein the first apparatus comprises an access node.

43. The first apparatus of claim 42, wherein the at least one transmitted signal comprises at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

44. The first apparatus of claim 42 or 43, wherein the at least one received signal comprises at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

45. The first apparatus of any of claims 33 through 41, wherein the first apparatus comprises a user equipment.

46. The first apparatus of claim 45, wherein the at least one transmitted signal comprises at least one of: an uplink signal, a physical uplink shared channel signal, a physical uplink control channel signal, or a reference signal.

47. The first apparatus of claim 45 or 46, wherein the at least one received signal comprises at least one of: a downlink signal, a physical downlink shared channel signal, a physical downlink control channel signal, a synchronization signal block, a physical broadcast channel signal, or a reference signal.

48. The first apparatus of any of claims 45 through 47, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the apparatus to: receive, from the second apparatus, a signal configuration, wherein the signal configuration comprises, at least, one or more phase noise pre- compensation related indications.

49. The first apparatus of claim 48, wherein the signal configuration further comprises at least one of: a phase tracking reference signal configuration, or a phase noise post-compensation configuration.

50. A method comprising: transmitting, with a first apparatus to a second apparatus, at least one signal; and receiving, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

51. A first apparatus comprising means for: transmitting, to a second apparatus, at least one signal; and receiving, from the second apparatus, at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

52. A non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.

53. A computer program comprising instructions stored thereon for performing at least the following: causing transmitting, with a first apparatus to a second apparatus, of at least one signal; and causing receiving, from the second apparatus, of at least one signal, wherein the at least one signal is phase noise pre-compensated based, at least partially, on the at least one transmitted signal.