Method and device for CSI (Channel State Information) compression in time domain

Abstract

Particularly, a method is disclosed, comprising: obtaining time domain and / or Doppler domain information based on measuring time variation of a channel from a tracking reference signal (TRS); and reporting time domain and / or Doppler domain information and channel state information (CSI), wherein the CSI is obtained by measuring a CSI reference signal (CSI-RS). Further, a method is disclosed, comprising: receiving time domain and / or Doppler domain information, and at least one channel state information (CSI); and reconstructing the time domain function based on the time domain and / or Doppler domain information and the precoder matrix based on the CSI. The invention further discloses a corresponding device, a computer program and a system.

Description

Technical Field

[0001] Various example embodiments according to the present disclosure relate to communication networks, such as wireless radio networks including base stations and mobile devices or user equipment (also referred to as user equipment (UE)) communicating with each other. In particular, various example embodiments according to the present disclosure relate to systems, apparatuses and methods for channel state information (CSI) compression in the time domain. Background Art

[0002] Various example embodiments according to the present disclosure relate to, but are not limited to, communication networks defined by 3GPP standards, such as the 5G standard, also referred to as New Radio (NR).

[0003] In 5G systems, especially in FDD operation, the gNB uses downlink reference signal (e.g., CSI-RS, SSB, etc.) transmission and CSI feedback from the UE to obtain the CSI required for precoding downlink (DL) data and demodulation reference signal (DMRS) on multiple layers, resource scheduling, etc. Summary of the invention

[0004] For convenience, a list of abbreviations used below has been given here:

[0005] AI

[0006] CSI Channel State Information

[0007] CSI-RS Channel State Information Reference Signal

[0008] CQI Channel Quality Indicator

[0009] CRI CSI-RS resource indicator

[0010] CNN Convolutional Neural Network

[0011] DMRS Demodulation Reference Signal

[0012] DL Downlink

[0013] NR New Radio

[0014] CSI-RS Channel State Information-Reference Signal

[0015] CSI-IM Channel State Information-Interference Measurement

[0016] DCI Downlink Control Information

[0017] DFT Discrete Fourier Transform

[0018] DCT Discrete Cosine Transform

[0019] EVD Eigenvalue Decomposition

[0020] FDD Frequency Division Duplex

[0021] Base stations in gNB NR

[0022] RAN Radio Access Network

[0023] RRC Radio Resource Control

[0024] MAC CE MAC Control Element

[0025] MCS Modulation Coding Scheme

[0026] ML Machine Learning

[0027] MU Multi-User

[0028] NN Neural Network

[0029] IE Information Elements

[0030] UCI Uplink Control Signal

[0031] UE User Equipment

[0032] UL Uplink

[0033] PMI Precoding matrix indicator

[0034] SU Single User

[0035] SRS Sounding Reference Signal

[0036] SVD Singular Value Decomposition

[0037] TRS (multiple) Tracking Reference Signals

[0038] According to various exemplary embodiments of the present disclosure, time domain channel tracking can be implemented, and / or time domain correlation and / or Doppler domain information can be added to the traditional Type-I / eType-II CSI report, for example, there is no need to measure multiple CSI-RS opportunities, and there is no need to change the combination coefficient in the traditional CSI report. Therefore, various exemplary embodiments can achieve improved signaling.

[0039] According to a first exemplary aspect, a method is disclosed, the method comprising:

[0040] -Acquire time domain and / or Doppler domain information based on measuring the time variation of the channel from the tracking reference signal TRS;

[0041] - Reporting time domain and / or Doppler domain information, and channel state information CSI, wherein the CSI is obtained by measuring a CSI reference signal CSI-RS.

[0042] For example, according to an exemplary aspect, a method is disclosed, the method comprising:

[0043] - Obtain at least one CSI reference signal CSI-RS to obtain at least one CSI, and obtain at least one tracking reference signal TRS;

[0044] -Measure the time variation of the channel based on TRS;

[0045] - obtaining time domain and / or Doppler domain information based on the time variation of the measurements;

[0046] - Reporting time domain and / or Doppler domain information, and at least one channel state information CSI, wherein the CSI is obtained by measuring the (obtained) CSI reference signal CSI-RS.

[0047] The method disclosed above (according to the first exemplary aspect) may be performed and / or controlled, for example, by an apparatus (e.g., a user equipment or UE). The terms user equipment and UE are used as interchangeable terms below. For example, the method may be performed and / or controlled by using at least one processor of a user equipment or UE.

[0048] A UE may be understood as a fixed device or a mobile device (e.g., a mobile telecommunication device or a mobile phone). For example, it may be a UE of a mobile communication network (e.g., 3G, LTE / 4G, 5G NR, 5G network, or future communication standards such as 6G). In addition, a UE may be, for example, a mobile phone, a smart phone, a tablet computer, a laptop computer, or any other mobile device. In various embodiments, a UE may be a vehicle for traveling in the air, in water, or on land, such as an airplane or a drone, a ship, or a car or a truck. A UE may also be a robot, a sensor device, a wearable device, an Internet of Things (IoT) device, a machine type communication (MTC) device, etc.

[0049] The components of the UE may be implemented in hardware and / or software. It may include, for example, at least one processor for executing computer program code for performing the required functions, at least one memory for storing program code, or both. Alternatively, it may include, for example, a circuit system designed to implement the required functions, such as implemented in a chipset or chip (such as an integrated circuit). Generally, the component may include, for example, one or more processing components or processors.

[0050] For example, a UE may include at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause an apparatus (e.g., UE) to at least perform and / or control a method according to an exemplary aspect.

[0051] The method disclosed above (according to the first exemplary aspect) can achieve time domain channel tracking, and / or add time domain correlation and / or Doppler domain information to the traditional Type-I / eType-I ICSI report, for example, without the need to measure multiple CSI-RS opportunities, and without changing the combining coefficients in the traditional CSI report. The method disclosed above (according to the first exemplary aspect) can achieve improved signaling.

[0052] According to a second exemplary aspect, a method is disclosed, the method comprising:

[0053] - receiving time domain and / or Doppler domain information, and at least one channel state information CSI;

[0054] - Reconstruct the time domain function based on the time domain and / or Doppler domain information and the CSI-based precoder matrix.

[0055] The method according to the second exemplary aspect may be performed, for example, by a network node (eg a gNB or a Radio Access Network RAN ​​node).

[0056] The method according to the second exemplary aspect can implement time domain channel tracking, and / or implement adding time domain correlation and / or Doppler domain information to the traditional Type-I / eType-I ICSI report, for example, without the need to measure multiple CSI-RS opportunities, and without changing the combining coefficients in the traditional CSI report. The method can implement improved signaling.

[0057] According to a third exemplary aspect, an apparatus is disclosed, the apparatus being configured to execute, and / or control, and / or comprising means for at least one processor and at least one memory comprising computer program code, and / or comprising at least one processor and at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the apparatus to at least execute:

[0058] - obtaining time domain and / or Doppler domain information based on the time variation of the measurements;

[0059] - Reporting time domain and / or Doppler domain information, and at least one channel state information CSI, wherein the CSI is obtained by measuring a CSI reference signal CSI-RS.

[0060] For example, the apparatus according to the third exemplary aspect may be, or include, a user equipment or UE.

[0061] The apparatus according to the third exemplary aspect can implement time domain channel tracking, and / or implement adding time domain correlation and / or Doppler domain information to a traditional Type-I / eType-I ICSI report, for example, without the need to measure multiple CSI-RS opportunities, and without the need to change the combining coefficients in the traditional CSI report. The apparatus can implement improved signaling.

[0062] According to a fourth exemplary aspect, an apparatus is disclosed, the apparatus being configured to execute, and / or control, and / or comprising means for at least one processor and at least one memory comprising computer program code, and / or comprising at least one processor and at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the apparatus to at least execute:

[0063] - obtaining time domain and / or Doppler domain information, and at least one channel state information CSI; and for example

[0064] - Reconstruct the time domain function based on the time domain and / or Doppler domain information and the CSI-based precoder matrix.

[0065] For example, the apparatus according to the fourth exemplary aspect may be, or include, a gNB or a network node, such as a Radio Access Network RAN ​​node.

[0066] The apparatus according to the fourth exemplary aspect can implement time domain channel tracking, and / or implement adding time domain correlation and / or Doppler domain information to a conventional Type-I / eType-I ICSI report, for example, without requiring measurement of multiple CSI-RS opportunities, and without requiring changes to the combining coefficients in the conventional CSI report. The apparatus can implement improved signaling.

[0067] According to a fifth exemplary aspect, a system is disclosed, the system comprising at least two devices, the at least two devices together performing the method according to the first and / or second exemplary aspect.

[0068] The system according to the fifth exemplary aspect may comprise a mobile entity or a part thereof, and a server or a part thereof, which together perform the method according to the first and / or exemplary aspects.The system according to the fifth exemplary aspect may for example be a RAN.

[0069] The system may include one or more devices, such as the device of the third exemplary aspect and / or the device of the fourth exemplary aspect, and / or a server, a server cloud, a gNB, a UE, and / or a mobile terminal (e.g., a mobile telecommunication device or a mobile phone).

[0070] The system according to the fifth exemplary aspect can implement time domain channel tracking, and / or implement adding time domain correlation and / or Doppler domain information to the traditional Type-I / eType-I ICSI report, for example, without the need to measure multiple CSI-RS opportunities, and without changing the combining coefficients in the traditional CSI report. The method can achieve improved signaling.

[0071] According to further exemplary aspects, a system is disclosed, comprising:

[0072] - at least one device according to the third exemplary aspect; and

[0073] - The device according to the fourth exemplary aspect.

[0074] The system may, for example, be the system according to the fifth exemplary aspect.

[0075] According to a sixth exemplary aspect, a computer program is disclosed which, when executed by a processor of an apparatus, causes the apparatus to perform the method according to the first and / or second exemplary aspect.

[0076] The computer program may be stored on a computer-readable storage medium, in particular on a tangible and / or non-transitory medium. The computer-readable storage medium may be, for example, a disk or a memory. The computer program may be stored in a computer-readable storage medium in the form of instructions encoding the computer-readable storage medium. The computer-readable storage medium may be used to participate in the operation of a device, such as an internal or external memory, such as a read-only memory (ROM) or a hard disk of a computer; or for the distribution of the program, such as an optical disk.

[0077] The computer program according to the sixth exemplary aspect may implement time domain channel tracking, and / or implement adding time domain correlation and / or Doppler domain information to a conventional Type-I / eType-I ICSI report, e.g., without requiring measurement of multiple CSI-RS opportunities, and without requiring changes to combining coefficients in conventional CSI reporting. The computer program may implement improved signaling.

[0078] According to a seventh exemplary aspect, a tangible and / or non-transitory storage medium is disclosed, the tangible and / or non-transitory storage medium comprising: instructions stored thereon for executing the method according to the first and / or second exemplary aspect.

[0079] The tangible and / or non-transitory storage medium according to the seventh exemplary aspect can implement time domain channel tracking and / or implement adding time domain correlation and / or Doppler domain information to a traditional Type-I / eType-I ICSI report, e.g., without requiring measurement of multiple CSI-RS opportunities and without requiring changes to combining coefficients in traditional CSI reporting. The computer program can implement improved signaling.

[0080] According to a further exemplary aspect, a method is disclosed, the method comprising steps, the apparatus of the third and / or fourth exemplary aspects being configured to perform the steps or having components for performing the steps. The method may be performed and / or controlled, for example, by an apparatus, such as a server, a server cloud, a gNB, and / or a mobile entity (e.g., a mobile telecommunication device or a mobile phone or a user equipment). Alternatively, the method may be performed and / or controlled by a plurality of apparatuses, such as a server cloud comprising at least two servers, or a system of apparatuses, such as a system comprising at least one gNB and at least one UE. For example, the method may be performed and / or controlled by using at least one processor of the apparatus.

[0081] According to another exemplary aspect, a device is disclosed, which is configured to execute, and / or control, and / or includes components for, and / or includes: at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the device to at least execute the method of the first and / or second exemplary aspect.

[0082] According to a further exemplary aspect, a computer program product is disclosed which, when executed by a processor of an apparatus, causes the apparatus to perform the method according to the first and / or second exemplary aspect.

[0083] According to a further exemplary aspect, a computer-readable storage medium is disclosed, the computer-readable storage medium comprising: a computer program according to the sixth exemplary aspect, and / or a computer program product as disclosed above.

[0084] The components of the apparatus according to any exemplary aspect may be implemented in hardware and / or software. It may include, for example, at least one processor for executing computer program code for performing the desired functions, at least one memory for storing program code, or both. Alternatively, it may include, for example, a circuit system designed or configured to implement the desired functions, such as implemented in a chipset or chip, such as an integrated circuit. Typically, the component may include, for example, one or more processing components or processors.

[0085] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0086] (a) hardware circuit implementation only (such as implementation in analog and / or digital circuitry); and

[0087] (b) a combination of hardware circuitry and software such as (where applicable):

[0088] (i) a combination of analog and / or digital hardware circuits and software / firmware; and

[0089] (ii) any portion of hardware processor(s) (including digital signal processor(s)) with software, software, and memory(s) that work together to enable a device (such as a mobile phone or server) to perform various functions; and

[0090] (c) Hardware circuits and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) to operate, but in which the software may not be present when not required for operation.

[0091] This definition of circuitry applies to all uses of the 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 only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0092] The apparatus disclosed above according to any aspect may be a module or component for a device, such as a chip. Alternatively, the apparatus disclosed according to any aspect may be a device, such as a server or a server cloud. The apparatus disclosed according to any aspect may include only the disclosed components, such as a part, a processor, a memory, or may also include one or more additional components.

[0093] Any disclosure herein relating to any exemplary aspect should be understood as the same disclosure regarding any subject matter according to the corresponding exemplary aspect, such as relating to apparatus, methods, computer programs, and computer-readable media, etc. Thus, for example, the disclosure of method steps should also be considered as the disclosure of components for performing and / or configured to perform the corresponding method steps. Similarly, the disclosure of components for performing and / or configured to perform method steps should also be considered as the disclosure of the method steps themselves. The same applies to any paragraphs describing at least one processor; and at least one memory including computer program code; at least one memory and computer program code are configured to, together with at least one processor, cause the apparatus to perform at least steps.

[0094] Any disclosure in this document relating to any exemplary aspect may enable time domain channel tracking, and / or enable adding time domain correlation and / or Doppler domain information to traditional Type-I / eType-IICSI reports, for example, without the need to measure multiple CSI-RS opportunities and without changing the combining coefficients in traditional CSI reporting, and / or the method may enable improved signaling.

[0095] Exemplary features and exemplary embodiments of all aspects are described in more detail below.

[0096] According to all disclosed exemplary aspects, obtaining time domain and / or Doppler domain information based on measuring the time variation of the channel from the tracking reference signal TRS may for example be or include:

[0097] - obtaining at least one tracking reference signal TRS;

[0098] -Measurement of the time variation of the channel based on TRS; and

[0099] - Obtaining time domain and / or Doppler domain information based on the time variation of the measurements.

[0100] Reporting time domain and / or Doppler domain information, and channel state information CSI, wherein the CSI is obtained by measuring the CSI reference signal CSI-RS, for example, may be or include obtaining (for example, measuring) at least one CSI reference signal CSI-RS, and reporting at least one channel state information CSI, wherein the CSI is obtained by measuring the (obtained) CSI reference signal CSI-RS. Reporting time domain and / or Doppler domain information, and channel state information CSI, wherein the CSI is obtained by measuring the CSI reference signal CSI-RS, for example, may be or include:

[0101] - Obtain at least one CSI reference signal CSI-RS to obtain at least one CSI and report at least one channel state information CSI.

[0102] The CSI may include a precoder matrix indicator (PMI), and / or a rank indicator indicating the number of layers reported.

[0103] The method according to the first and / or second exemplary aspect may be a method for reference signal RS measurement and reporting.

[0104] Based on measuring the time variation of the channel from the tracking reference signal, obtaining time domain and / or Doppler domain information, and / or reporting time domain and / or Doppler domain information, and channel state information CSI, wherein the CSI is obtained by measuring the CSI reference signal CSI-RS, for example, which can be performed by the user equipment. The reporting can be performed by the user equipment, and can be reported to a network node (for example, a radio access network RAN ​​node). Reporting the time domain and / or Doppler domain information and the channel state information CSI can be reporting the time domain and / or Doppler domain information and the channel state information CSI to the network node (for example, reported by the user equipment).

[0105] A CSI reference signal (CSI-RS) may be understood as a downlink reference signal, e.g., intended to be used by a device to obtain downlink channel state information (CSI), e.g., by measuring the CSI-RS. A specific instance of a CSI-RS may be configured for time / frequency tracking (e.g., tracking in the time and / or Doppler domain) and mobility measurement. The CSI may include a precoder matrix indicator (PMI), and / or a rank indicator indicating the number of layers reported. A tracking reference signal (TRS) may be understood as a reference signal, e.g., intended to assist a device in time and frequency tracking. A specific CSI-RS configuration may, for example, be used for TRS purposes. A tracking reference signal (TRS) may be a specific CSI-RS.

[0106] The time domain and / or Doppler domain information may be understood, for example, as information related to the time domain and / or Doppler domain, respectively. The time domain information may, for example, include a time domain (TD) correlation value. The Doppler domain information may, for example, include a Doppler domain (DD) codebook component. The time domain and / or Doppler domain information may, for example, include (for example, only include) non-zero coefficients associated with D Doppler domain (DD) codebook components, D≤Nt, where Nt may be the number of time domain (TD) correlation values.

[0107] Time variation (eg, time variation of a channel) may be understood as any variation of a signal transmitted in the channel over time.

[0108] A time domain function may be understood as a function in the time domain, such as a function of time. A time domain function may describe how a signal changes over time, and a Doppler domain function may provide a representation of the time domain function in the transform domain after applying a transform based on an orthogonal basis function. The time domain function may be, for example, a time correlation function, such as a normalized time correlation function, such as at a time lag t j The function defined at:

[0109]

[0110] where t jIt can be defined by the network (eg RAN) configuring the minimum time unit T, so that all time lag values ​​are multiples of T. As an example, T = 2T sym , where T sym is the symbol duration, the time lag (value) can be indexed by its normalized duration, so that t2 = 2T = 4T sym t5=5T=10T sym Etc. In such a case, T = t1 holds. h(t) may be the TRS measurement at time t. Time lag t j The time correlation r(t j ) can be obtained by averaging the measurements of one / at least one acquired TRS (e.g. r(t2) and r(t7) can be obtained, for example, by averaging one / at least one of the obtained TRSs. The average of the measurements is calculated, and for r(t2) there is {τ 2，0 , τ 2,1}={4T sym , 18T sym}, and for r(t7) has {τ 7,0 , τ 7,1}={4T sym , 8T sym If more than one TRS is acquired (eg configured for time / Doppler reporting), the averaging in the time correlation function may, for example, be extended to more than one (eg multiple) TRS (measurements). This may improve measurement accuracy.

[0111] The PMI can be understood as a set of precoder matrix indices corresponding to one or more precoder matrices. The precoder matrix can be formed by a combination of multiple components, each component indicated by a subset of the index of the PMI. The precoder matrix can be, for example, or include a set of weights, such as applied to the tx antenna for data / DMRS transmission. The set of rules that define how to map the PMI to the corresponding precoder matrix, or map a subset of the PMI index to the components of the corresponding precoder matrix can be called a codebook. The codebook can be selected from a set of possible codebooks, for example, a codebook defined in the standard based on, for example, the codebook type, the possible number of transmission layers for downlink transmission, and CSI reporting configuration parameters (such as antenna panel size).

[0112] According to an exemplary embodiment of the method based on the first exemplary aspect and / or the apparatus based on the third exemplary aspect, the method further comprises, and / or the apparatus further comprises: means for at least one memory and computer program code, and / or at least one memory and computer program code, the at least one memory and computer program code being further configured to, together with at least one processor, cause the apparatus to at least perform:

[0113] - obtaining (e.g., receiving or configuring) a first configuration to report Nt time-domain correlation values ​​calculated from the TRS, and / or to report non-zero coefficients associated with D Doppler-domain codebook components, D≤Nt, where Nt and D are integers; and / or

[0114] - Acquiring (eg, receiving or configuring) a second configuration to provide TRS-based time domain and / or Doppler domain measurements in a wideband format or in a sub-band format.

[0115] Acquiring the first and / or second configuration may be receiving or configuring (eg by the network node) the first and / or second configuration. For example, the user equipment may receive the first and / or second configuration, eg from the network node.

[0116] According to exemplary embodiments of all exemplary aspects, the Doppler domain codebook component comprises: a discrete cosine transform DCT based codebook component and / or a discrete Fourier transform DFT based codebook component.

[0117] According to exemplary embodiments of the method according to the first exemplary aspect and / or the apparatus according to the third exemplary aspect, the time domain and / or Doppler domain information and the CSI are reported to the network node separately. For example, the CSI and in particular the PMI (precoder matrix indicator) can be encoded separately from the time and / or Doppler domain information and can be used, for example, without the time and / or Doppler domain information.

[0118] As another exemplary embodiment, an apparatus (e.g., a user equipment or UE) may report separate time and / or Doppler domain information (e.g., including time and / or Doppler quantity) for multiple FD basis components. For example, the time domain information may be subband time information. For example, time domain information (e.g., subband time information) and / or Doppler information may be provided by reporting separate correlation and / or Doppler coefficients for different FD basis components. For example, a user equipment may report separate time and / or Doppler domain quantities for multiple FD basis components.

[0119] According to an exemplary embodiment of a method based on the first exemplary aspect and / or an apparatus based on the third exemplary aspect, TRS-based time domain and / or Doppler domain information is reported for a corresponding (e.g., each) layer of a precoder matrix indicator reported in the CSI.

[0120] According to an exemplary embodiment of the method based on the second exemplary aspect and / or the apparatus based on the fourth exemplary aspect, the method further comprises, and / or the apparatus further comprises: means for at least one memory and computer program code, and / or at least one memory and computer program code, the at least one memory and computer program code being further configured to, together with at least one processor, cause the apparatus to at least perform:

[0121] - Providing a first configuration (e.g., configuring; e.g., by a network node, e.g., to a user equipment) to report Nt time-domain correlation values ​​calculated from a TRS, and / or to report non-zero coefficients associated with D Doppler-domain codebook components, D≤Nt, where Nt and D are integers.

[0122] According to an exemplary embodiment of the method based on the first exemplary aspect and / or the apparatus based on the third exemplary aspect, the method further comprises, and / or the apparatus further comprises: means for at least one memory and computer program code, and / or at least one memory and computer program code, the at least one memory and computer program code being further configured to, together with at least one processor, cause the apparatus to at least perform:

[0123] - Obtain at least one CSI reference signal CSI-RS to obtain at least one CSI, and obtain at least one tracking reference signal TRS;

[0124] -Measure the time variation of the channel based on TRS.

[0125] The CSI may be acquired by measuring at least one CSI reference signal CSI-RS (obtained). Acquiring at least one CSI reference signal CSI-RS for acquiring at least one CSI may include: measuring the at least one CSI reference signal obtained.

[0126] According to an exemplary embodiment of the method based on the first exemplary aspect and / or the apparatus based on the third exemplary aspect, reporting time domain and / or Doppler domain information includes: reporting Nt time domain correlation values ​​calculated from the TRS, and / or reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers.

[0127] According to exemplary embodiments of the method based on the first exemplary aspect and / or the apparatus based on the third exemplary aspect, reporting of time domain and / or Doppler domain information is performed in a wideband form or a sub-band form.

[0128] According to an exemplary embodiment of the method based on the first exemplary aspect and / or the apparatus based on the third exemplary aspect, reporting time domain and / or Doppler domain information includes: reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers, wherein the Doppler domain codebook components include: codebook components based on discrete cosine transform DCT and / or DFT.

[0129] According to exemplary embodiments of the method according to the first exemplary aspect and / or the apparatus according to the third exemplary aspect, time domain and / or Doppler domain information, and CSI are reported separately.

[0130] According to an exemplary embodiment of the method based on the first exemplary aspect and / or the apparatus based on the third exemplary aspect, reporting of time domain and / or Doppler domain information is performed for the corresponding (e.g., each) layer of the precoder matrix indicator reported in the CSI.

[0131] According to an exemplary embodiment of the method based on the second exemplary aspect and / or the apparatus based on the fourth exemplary aspect, the method further comprises, and / or the apparatus further comprises: means for at least one memory and computer program code, and / or at least one memory and computer program code, the at least one memory and computer program code being further configured to, together with at least one processor, cause the apparatus to at least perform:

[0132] A second configuration is provided (eg, configured; eg, by a network node, eg, to a user equipment) to provide TRS-based time domain and / or Doppler domain measurements in a wideband form or in a sub-band form.

[0133] Providing the first configuration and / or the second configuration may be or may include sending the configuration, for example sending the configuration by the network node to the user equipment.

[0134] According to exemplary embodiments of the method according to the second exemplary aspect and / or the apparatus according to the fourth exemplary aspect, the Doppler domain codebook component comprises: a discrete cosine transform DCT-based and / or DFT-based codebook component.

[0135] According to exemplary embodiments of the method based on the second exemplary aspect and / or the apparatus based on the fourth exemplary aspect, time domain and / or Doppler domain information and CSI are acquired separately (eg, from a user equipment).

[0136] According to an exemplary embodiment of a method based on the second exemplary aspect and / or an apparatus based on the fourth exemplary aspect, TRS-based time domain and / or Doppler domain information (e.g., obtained from a user equipment) is obtained for each layer in a precoder matrix indicator of the CSI.

[0137] According to an exemplary embodiment of the method based on the second exemplary aspect and / or the apparatus based on the fourth exemplary aspect, the method further comprises, and / or the apparatus further comprises: means for at least one memory and computer program code, and / or at least one memory and computer program code, the at least one memory and computer program code being further configured to, together with at least one processor, cause the apparatus to at least perform:

[0138] - providing a first configuration to a further apparatus to report Nt time domain correlation values ​​calculated from the TRS, and / or to report non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers.

[0139] The apparatus according to the fourth exemplary aspect may for example be a network node.The further apparatus may for example be a user equipment.

[0140] According to an exemplary embodiment of the method based on the second exemplary aspect and / or the apparatus based on the fourth exemplary aspect, the method further comprises, and / or the apparatus further comprises: means for at least one memory and computer program code, and / or at least one memory and computer program code, the at least one memory and computer program code being further configured to, together with at least one processor, cause the apparatus to at least perform:

[0141] - Providing a second configuration to a further device to provide TRS based time domain and / or Doppler domain measurements in a wideband format or in a sub-band format.

[0142] According to an exemplary embodiment of the method based on the second exemplary aspect and / or the apparatus based on the fourth exemplary aspect, the method further comprises, and / or the apparatus further comprises: means for at least one memory and computer program code, and / or at least one memory and computer program code, the at least one memory and computer program code being further configured to, together with at least one processor, cause the apparatus to at least perform:

[0143] The precoder is reconstructed based on the acquired time domain and / or Doppler domain information.

[0144] For example, the CSI may include time domain and / or Doppler domain information.

[0145] According to exemplary embodiments of the method according to the second exemplary aspect and / or the apparatus according to the fourth exemplary aspect, time domain and / or Doppler domain information and CSI are acquired separately.

[0146] According to exemplary embodiments of the method based on the second exemplary aspect and / or the apparatus based on the fourth exemplary aspect, TRS-based time domain and / or Doppler domain information is acquired for each layer of the precoder matrix indicator of the CSI.

[0147] According to exemplary embodiments of all exemplary aspects, a method for measuring time variations of a channel from a TRS signal is disclosed, including, for example, reporting (corresponding) channel state information.

[0148] According to exemplary embodiments of all exemplary aspects, obtaining time domain and / or Doppler domain information based on measuring the time variation of the channel from a tracking reference signal TRS and / or measuring the time variation of the channel based on TRS may include determining the time variation of non-zero combination coefficients (e.g., traditional Type-I or Type-IIPMI).

[0149] According to exemplary embodiments of all exemplary aspects, reporting and / or obtaining time domain and / or Doppler domain information may include: reporting and / or obtaining (eg, only reporting or obtaining) non-zero combining coefficients.

[0150] According to exemplary embodiments of all exemplary aspects, reporting and / or obtaining time domain and / or Doppler domain information may include: reporting and / or obtaining a report including time correlation at a predetermined time lag, and / or transform coefficients associated with a set of basis components (e.g., discrete cosine transform basis components) obtained from a codebook.

[0151] The exemplary embodiment of the method according to the first exemplary aspect further comprises, and / or the exemplary embodiment of the apparatus according to the third exemplary aspect is further configured to execute and / or comprises: means for at least one memory and a computer program code, and / or at least one memory and a computer program code, the at least one memory and the computer program code being further configured to, together with at least one processor, cause the apparatus to at least execute:

[0152] - determining a maximum time-dependent lag based at least in part on the acquired (eg measured) maximum time interval of the TRS (resource) and optionally based at least in part on:

[0153] -The time unit T corresponds to a fraction T = t1, where N4 is the dimension of the codebook and T is the symbol duration T sym multiples of.

[0154] According to exemplary embodiments of all exemplary aspects, the codebook may, for example, be a time-dependent codebook configured for compressing a discrete cosine transform basis.

[0155] According to exemplary embodiments of all exemplary aspects, (e.g., time domain and / or Doppler domain) information may be used to determine the temporal variation of non-zero combining coefficients of a conventional Type-I or Type-I IPMI. TRS temporal measurements may be reported, for example, as temporal correlations at predetermined time lags, or as transform coefficients associated with a set of basis components obtained from a codebook. Maximum temporal correlation lag It can be determined, for example, by the maximum time interval of the measured TRS resources, and the time unit T can correspond to the fraction T = t1, where N4 is the codebook dimension and T is the symbol duration T sym For example, a codebook configured for compressing time correlation may be formed, for example, from a discrete cosine transform basis.

[0156] The features and exemplary embodiments described above may be equally applicable to different aspects.

[0157] It should be understood that the descriptions in this section are provided by way of example only and not limitation.

[0158] Other features will be apparent from the following detailed description considered in conjunction with the accompanying drawings. It should be understood, however, that the drawings are for illustration purposes only and not as a definition of limitation, for which reference should be made to the appended claims. It should also be understood that the drawings are not drawn to scale and that they are intended only to conceptually illustrate the structures and procedures described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0159] The attached figure shows:

[0160] Figure 1 a schematic high-level block diagram of an exemplary system;

[0161] Figure 2a a flow chart showing an example embodiment of the method according to the first exemplary aspect;

[0162] Figure 2b a flow chart showing an example embodiment of the method according to the first exemplary aspect;

[0163] Figure 3 a flow chart showing an example embodiment of a method according to the second exemplary aspect;

[0164] Figure 4 Example measurement timeline for conventional CSI reporting;

[0165] Figure 5 Exemplary resource element locations occupied by TRS opportunities;

[0166] Figure 6a from Figure 5 An exemplary time correlation measured by an exemplary TRS resource;

[0167] Figure 6b from Figure 5 An exemplary time correlation measured by an exemplary TRS resource;

[0168] Figure 7 A high-level block diagram of an exemplary method according to the first exemplary aspect, and an exemplary method according to the second exemplary aspect;

[0169] Figure 8 A high-level block diagram of an exemplary method according to the first exemplary aspect, and an exemplary method according to the second exemplary aspect;

[0170] Fig. 9 A high-level block diagram of an exemplary method according to the first exemplary aspect, and an exemplary method according to the second exemplary aspect;

[0171] Fig.10 A high-level block diagram of an exemplary method according to the first exemplary aspect, and an exemplary method according to the second exemplary aspect;

[0172] Fig.11 Schematic block diagram of an example embodiment of an apparatus according to the first aspect, and / or an example embodiment of an apparatus configured to perform a method according to the second exemplary aspect. DETAILED DESCRIPTION

[0173] The following description helps to deepen the understanding, and should be understood to supplement the description provided in the above invention content section of this specification and read together with it. Certain aspects may have different terms, such as those provided in the above description. However, it will be understood by those skilled in the art that these terms refer to the same subject matter, such as in a more specific manner. For example, the time domain and / or Doppler domain can be referred to as time / Doppler, or TD / DD. The time domain and / or Doppler domain information can be referred to as time domain correlation / Doppler domain information. The discrete cosine transform DCT codebook components can be referred to as DCT basis components, or DCT basis vectors.

[0174] Figure 1 is a schematic high-level block diagram of a system 100 according to all exemplary aspects. The system 100 comprises one or more devices 101, which represent, for example, a device according to the second exemplary aspect, and another device 102, which represents, for example, a device according to the first exemplary aspect. The devices 101, 102 may be, for example, part of a mobile communication network or RAN.

[0175] Figure 2a and Figure 2b200_1 and / or 200_2 may be performed by at least one device 102 (e.g., user equipment). Additionally or alternatively, flowcharts 200_1 and / or 200_2 may be performed by a system 100 comprising more than one device.

[0176] exist Figure 2a In the first step 201 of the flowchart 200_1, for example, the user equipment obtains time domain and / or Doppler domain information based on measuring the time variation of the channel from the tracking reference signal TRS. The TRS may be a specific CSI-RS.

[0177] In the second step 202, for example, the user equipment reports the time domain and / or Doppler domain information and the channel state information CSI to, for example, a network node, wherein the CSI is obtained by measuring a CSI reference signal CSI-RS.

[0178] exist Figure 2b In the first step 203 of the flowchart 200_2, for example, the user equipment 102 acquires at least one CSI reference signal CSI-RS for acquiring at least one CSI, and acquires at least one tracking reference signal TRS. The acquired CSI-RS may be measured to acquire (i.e., to acquire or to collect or to measure) at least one CSI.

[0179] In a second step 204, the time variation of the TRS-based channel is measured, for example by the user equipment 102.

[0180] In a third step 205, time domain and / or Doppler domain information is acquired, for example by the user equipment 102, based on the measured time variation.

[0181] In a fourth step 206 , for example, the user equipment 102 reports time domain and / or Doppler domain information, and at least one channel state information CSI to, for example, the network node 101 .

[0182] Figure 3 is a flow chart illustrating an exemplary embodiment of a method according to the second exemplary aspect. Flowchart 300 may be performed, for example, by at least one apparatus 101 (e.g., a network node or gNB 101). Additionally or alternatively, flow chart 300 may be performed by a system 100 comprising more than one apparatus (e.g., comprising a server or a server cloud).

[0183] In a first step 301 of the flowchart 300 , time domain and / or Doppler domain information and at least one channel state information CSI are obtained, for example, by a network node (eg, from the user equipment 102 ).

[0184] In a second step 302, a time domain function is reconstructed, for example by a network node, based on time domain and / or Doppler domain information and a precoder matrix based on the CSI.

[0185] In NR, the gNB may send a DL reference signal CSI-RS so that the UE may, for example, measure the DL channel. Based on this measurement, the UE may determine (e.g., calculate) a CSI quantity for reporting based on a Type-I or Type-II codebook. The CSI quantity configured for reporting may include a precoder matrix indicator (PMI), and a corresponding channel quality indicator (CQI). The Type-I codebook may provide a coarse representation of the precoder, such as indicated by a precoder matrix indication (PMI), for example, by selecting a single DFT beam per layer, per subband. The same beam may be used in both polarizations of the transmit antenna array, with a co-phase factor between the two polarizations. The Type-II codebook may provide a richer precoder representation, for example by representing the precoding weights per layer, per subband as a linear combination of L DFT beams.

[0186] For Type-I and Type-II (e.g., Release 15) codebooks, the precoding matrix for each layer and across at least two (e.g., all) subbands (e.g., configured for reporting, e.g., for subband reporting) may follow the codebook structure:

[0187] W=W1W2

[0188] Where W1 can be a matrix of wideband DFT beams of size 2N1N2×2L, and can be formed by L orthogonal vectors / beams for each polarization p, for example, selected from a set of 2D oversampled DFT beams, where N1 and N2 can be the number of antenna ports in the horizontal and vertical dimensions of the transmitting rectangular array. Such an operation can achieve compression in the spatial domain (SD), so the resulting 2L beams can also be called SD components. In the antenna domain, there may be a transformation duality between, for example, a two-dimensional rectangular antenna array domain and a two-dimensional angle domain, so that the 2D DFT beams can be associated with a pair of discrete angles in azimuth and elevation. W2 can be a subband matrix of size 2L×N3, for example, in the case of Type-I, it contains, for example, beam selection and / or co-phase factors between the corresponding (for example, each) two polarizations in the N3 subbands. For example, for Type-II, W2 can contain complex-valued combination coefficients for L beams for each polarization.

[0189] For Type-II disclosed above, the precoder vector for layer l=1, ..., ν, and subband s=0, ..., N3-1 can be extended as follows, for example:

[0190]

[0191] Where W s l The size is 2N1N2×1, is the i-th SD basis component of size 2N1N2×1, is the subband amplitude of the combined coefficient for SD component i, layer l and subband s, is the subband phase of the combined coefficients for SD component i, layer l and subband s, and γ s，l is a normalization factor to ensure unit norm of the precoded vector.

[0192] For eType-II (e.g., Release 16) and FeType-II (further enhanced Type II; Release 17) codebooks, compression operations may be added in the frequency domain, such as a precoding matrix configured, for example, for each layer reported and across at least two (e.g., all) subbands may follow the codebook structure:

[0193]

[0194] Where W f It can be a matrix of FD basis components of size N3×M, and can be formed by M orthogonal vectors selected from the DFT codebook. W2 can be a 2L×M matrix containing combination coefficients for respective (e.g., each) pairs of SD and FD basis components. The FD basis component can, for example, refer to a component in the delay domain, which can be a dual transform domain of the frequency (i.e., subband) domain. Therefore, the FD basis component can be a delay domain basis component. The FeType-II codebook disclosed above can be a new port selection codebook for partial UL / DL channel reciprocity in FDD, which can, for example, utilize the gNB's estimate of the main beam and delay to, for example, precode the CSI-RS port, and, for example, simplify the FD compression operation at the UE.

[0195] For the eType-II disclosed above, the precoder vector for layer l=1, ..., ν, and subband s=0, ..., N3-1 can be extended as follows:

[0196]

[0197] Where W s l The size of can be 2N1N2×1, and Can be the fth FD basis component The sth element of , with a size of N3×1.

[0198] In this codebook structure, the UE may, for example, report one complex-valued combining coefficient per layer and per polarization for at least one pair (eg, each pair) of SD-FD basis components. For example, for 2N1N2 transmit antennas and N3 subbands, the eType-II precoder can be represented as a 2N1N2·N3×1 vector, which is formed by a linear combination of L·M SD-FD basis component pairs, and can be obtained by Given, where Denotes the Kronecker product. For simplicity, the 2N1N2·N3×1 precoder for eType-II can be rewritten as follows, where the precoder normalization is omitted:

[0199]

[0200] For example, in Release 18, new enhancements to CSI reporting may be considered by utilizing time-domain correlation / Doppler domain information, e.g. to assist DL precoding, according to the following description (as described in 3GPP RAN#94-e):

[0201] (First) study (and if justified) specify CSI reporting enhancement for high / medium UE speeds for FR1 by leveraging time-domain correlation / Doppler domain information to assist DL precoding as follows:

[0202] -Release 16 / 17 Type-II codebook refinement, no need to modify the spatial and frequency domain basis.

[0203] -UE reports the time domain channel characteristics measured via CSI-RS for tracking.

[0204] Time domain correlation and Doppler domain spectrum may for example form a third "dual domain" pair in addition to antenna / angle and frequency / delay, such as may be considered in Release 15 / 16 / 17.

[0205] A method (e.g., a mechanism) for CSI measurement and reporting may be provided, which may include Doppler domain compression. The method may be based on UE measurements of bursts, such as N4 sets of CSI-RS resources, UE selection of, for example, D Doppler domain basis components, and configuration of a DFT codebook for selecting Doppler domain basis components. Conventional eType-IICSI feedback may be modified by, for example, reporting a single set of non-zero combination coefficients for three codebook-based basis components (spatial, delay, and Doppler). Thus, the UE may report a combination coefficient for each (e.g., each) selected spatial, delay, Doppler component triplet. In order to obtain such a single combination coefficient, the method may include measuring the spatial, delay, and Doppler components on the same CSI-RS signal, which may be repeated in a burst manner to allow joint determination of the spatial, delay, and Doppler basis components. For example, for 2N1N2 transmit antennas, N3 subbands, and N4 time samples, the precoder can be represented as a 2N1N2.N3·N4×1 vector, for example, formed by a linear combination of L·M·D SD-FD Doppler basis component triplets, which are formed by Given, where represents the Doppler domain basis component. The 2N1N2·N3·N4×1 precoder can be rewritten as follows, where the precoder normalization is omitted for simplicity:

[0206]

[0207] The UE can be configured to determine (e.g., calculate) the traditional Type-I or Type-II from the CSI-RS resources. Additionally, the UE can be configured to measure and report time-related or Doppler coefficients from one or more TRS opportunities. TRS is a special type of CSI-RS, for example, used to track CFO (carrier frequency offset between the gNB and UE carrier frequencies) and TFO (time frequency offset, i.e., the clock period offset used for sampling at the gNB and UE), and for Doppler-related measurements. Both CFO and TFO may be caused by oscillator frequency differences between the gNB and the UE, while Doppler spread may be mainly caused by the mobility of the UE. The TRS resource set may contain two or four sets with a period of 2 μ X p The periodic CSI-RS resources of time slots, where X p=10, 20, 40 or 80, and where μ is related to the subcarrier spacing (SCS), i.e., μ=0, 1, 2, 3, 4 for 15, 30, 60, 120, 240 kHz, respectively. The slot offsets for two or four sets of CSI-RS resources are configured such that: the first pair of resources is sent in one slot, and the second pair of resources (if configured) is sent in the next (adjacent) slot. All four sets of resources are single-port resources with a density of 3.

[0208] Figure 4 An exemplary measurement timeline for conventional CSI reporting with additional TD / DD reporting is shown, where CSI-RS measurement opportunities are labeled RS1, 2, 3, ..., and TRS measurement opportunities are labeled TRS1, 2, 3, .... CSI reports are labeled R1, 2, 3, ... . Figure 3 The diagram in shows an exemplary illustration of the relative positions of CSI-RS and TRS measurement opportunities with respect to CSI reporting in a time slot, but the temporal behavior of CSI reporting may differ from the examples in the diagram. For example, Type-II reporting may be semi-persistent or aperiodic, and reference signals may be configured as periodic, semi-persistent, or aperiodic.

[0209] Figure 5 Exemplary resource element locations occupied by TRS opportunities are shown, for example configured with four sets of resources over two consecutive time slots.The UE may be configured to determine (eg, calculate) a normalized time correlation of the TRS signal. Figure 5 shows how a single TRS opportunity allows determination (eg, calculation) of the t =4 lag time correlation: t2, t5, t7, t9. The network can configure the minimum time unit T so that all relevant lag values ​​are multiples of T. In the example, T = 2T sym , where T sym is the symbol duration, and the hysteresis values ​​are indexed by their normalized duration, so t2 = 2T = 4T sym t5=5T=10T sym Etc. It is noteworthy that in this notation, T=t1.

[0210] In an exemplary implementation, the UE may determine (eg, calculate) the hysteresis t j Such a normalized time correlation at is as follows:

[0211]

[0212] where h(t) is the TRS measurement at time t. Lag t j The time correlation can be obtained by The measurements are averaged to obtain the Figure 5 In the example, r(t2) and r(t7) can be obtained by The average of the measurements is calculated, and for r(t2) there is {τ 2，0 , τ 2,1}={4T sym , 18T sym ), and for r(t7) with {τ 7,0 , τ 7,1}={4T sym , 8T sym ). If multiple TRS occasions are configured for time and / or Doppler reporting, the averaging in the time correlation function (see above) will be spread over multiple TRS measurement occasions, which can increase measurement accuracy.

[0213] Figure 6a and 6b Shows from Figure 5 Example of time correlation of TRS resource measurements. Figure 6a An exemplary normalized time correlation is shown, and Figure 6b The corresponding exemplary normalized Doppler spectrum is shown. It also shows the relationship between the time correlation obtained by applying the Doppler domain basis component defined by the Doppler codebook and the Doppler spectrum. The maximum lag of the time correlation normalized by the time unit T can provide the length N4 of the Doppler domain basis component, i.e.

[0214] N4 = (maximum time-dependent lag) / (time unit T)

[0215] In practice, the value of N4 can be configured by the size of the Doppler domain basis vectors, and the time unit T can be configured as the symbol duration T sym multiples of.

[0216] Figure 7 , Figure 8 , Fig. 9 and Fig.10 A high level block diagram of an exemplary method according to a first exemplary aspect and an exemplary method according to a second exemplary aspect is shown. On the right side an exemplary embodiment of the method according to the first aspect is shown, while on the left side an exemplary embodiment of the method according to the second aspect is shown. Figure 7 , Figure 8 , Fig. 9 and Fig.10 The interaction of the two methods is shown, for example between the UE side and the gNB side.

[0217] For example, the method according to the first exemplary aspect may include calculating at least one subband measurement or at least one wideband measurement, for example, from multiple subband measurements. The method according to the first exemplary aspect may also include applying the basis component to time-related measurements, for example, in the time / Doppler domain, and / or quantizing the time and / or Doppler coefficients. For example, the method according to the first exemplary aspect may also include calculating CSI, for example, based on or calculated in the antenna / angle domain and / or frequency / delay domain, and / or may also include calculating port selection CSI. For example, the method according to the first exemplary aspect may also include calculating PMI, for example, calculating a certain number (for example, N4) of PMIs at certain times. For example, the method according to the second exemplary aspect may include reconstructing a precoder. For example, the method according to the second exemplary aspect may also include: determining (for example, calculating) the strongest beam based on SRS, and delaying and / or precoding CSI-RS across antennas and / or frequencies (for example, in the antenna / angle domain or the frequency / delay domain). For example, the precoder may be as described above, or as described below, and / or at least one of the following:

[0218] W (t) =W1W2 (t) ;

[0219]

[0220] Among them, W1, W2, W3, W f 、u d It can be, for example, any type defined in this specification.

[0221] Specifically, Figure 7 , Figure 8 , Fig. 9 and Fig.10 A high-level block diagram of an exemplary CSI calculation at the UE with additional time and / or Doppler domain information is shown, and how the precoder and precoder matrix are derived from the CSI quantity, respectively. In the exemplary scheme, the precoder matrix at time t=t0 can be provided by the traditional CSI. The precoder matrix at can be obtained by combining the traditional CSI reports (Type-I or Type-II) measured from or based on CSI-RS measurements, and additional time and / or Doppler domain information measured from TRS. TRS-based time-correlated / Doppler domain feedback can be used to obtain the variation of non-zero combining coefficients (W2) over time, while the SD and FD basis components (W1 and W2, respectively) f ) may be assumed to be the same for N4 precoders. In some exemplary embodiments, the UE may be configured to report N t time-correlated samples, for example so that the Doppler domain compression operation is omitted.

[0222] In one exemplary configuration, TRS measurements in the time / Doppler domain can be used to estimate the time variation of each (e.g., each) subband in the CSI reporting band, respectively, and the UE reports the time / Doppler quantity (i.e., time domain and / or Doppler domain information) in the form of subbands. In another exemplary configuration, the time / Doppler domain quantity can be assumed to be wideband, that is, it is common for all channel delay taps corresponding to the FD component selected in the CSI-RS based PMI calculation. For example, in this case, the UE can report the time / Doppler related quantity in a wideband form. In another exemplary configuration, TRS measurements in the time / Doppler domain can be used to estimate the time variation of at least one (e.g., each) of the FD base components selected in the CSI-RS based PMI calculation. For example, in this case, the UE can report separate time / Doppler domain quantities for multiple FD base components.

[0223] For example, suppose W TRS is a N4×N3 matrix containing the values ​​for each (eg, each) subband and N t The time-dependent measurement of the lag value r(t j ). If the corresponding hysteresis value cannot be measured directly, then W TRS N4-N t The line can be zero. In the case of wideband time / Doppler reporting, such as Figure 7 and Figure 8 As shown in , the broadband time correlation value can be obtained from the t The lag values ​​are determined (e.g., calculated) from the subband measurements and arranged in the N4×1 vector w T middle.

[0224] In the case of sub-band time / Doppler reporting, such as Fig. 9 In the above example, the M FD basis components selected by the traditional Type-II CSI calculation are represented by the N3×M DFT matrix W f It can be applied to W TRS To obtain the time correlation matrix W of the FD transform T =W TRS W f .

[0225] In an exemplary embodiment, the time-dependent values ​​may be reported without Doppler compression, so that for wideband TD reporting, the UE reports w T Non-zero elements of , or for sub-band TD reporting, UE reports W T The non-zero elements of .

[0226] In another exemplary embodiment, a Doppler compression codebook is configured, which is formed by basis vectors of length N4. The D vectors from the codebook (called DD basis components) can be configured by the network or selected by the UE. These vectors can be arranged in a matrix W of N4×D D and applied to w T or W T To obtain the DD combination coefficients. For broadband DD reporting, these coefficients can be represented by a D×1 vector, For subband DD reporting, these coefficients can be represented by a D×M matrix, Before applying the DD transformation, the UE may t The non-zero correlation values ​​are interpolated so that all N4 lags contain non-zero correlation values.

[0227] The gNB can receive the legacy CSI from which it can obtain the precoder matrix for layer l as:

[0228] W=W1 W2

[0229] For Type-I reporting, or:

[0230]

[0231] For Type-II reporting. In addition, the gNB can, for example, receive the time correlation coefficient, which is reported as w for wideband TD T , or W for subband TD T , and / or DD combining coefficients associated with the D basis components, reported as w3 for wideband DD or as W3 for subband DD. In the case of DD reporting, the gNB can apply the decompression operation w for wideband reporting and subband reporting respectively. T =W D w3 or W T =W D W3, to reconstruct the TD correlation function. For example, finally, in time (e.g., t0=0), the precoder is reconstructed, for example, for broadband reporting, as follows:

[0232] or

[0233] have

[0234]

[0235] Or for example, for subband reporting, it is as follows

[0236]

[0237] have

[0238]

[0239] in represents the Kronecker product and ⊙ represents the Hadamard product or element-wise product.

[0240] Fig. 9 The exemplary block diagram shows how to combine sub-band or wideband TRS-based time / Doppler domain reporting with Type-I or Type-II sub-band or wideband CSI reporting, respectively.

[0241] The UE can calculate N4 time domain subband measurements w from the TRS. T , for each (eg, each) subband s with s=0, ..., N3-1. The UE may insert N t time-dependent lags, N t ≤N4, to obtain N4 samples. Alternatively, the UE can measure W from the N4×N3 TRS correlation TRS To calculate N4 broadband measurements w T . (Then) the UE can convert the D DD basis components (W D ), D≤N4, applied to vector w of length N4 T , to obtain a compressed representation of the time domain measurement in a vector w3 of length D. (Then) these D combined coefficients may be quantized and (e.g. only) non-zero values ​​may be reported. The PMI non-zero coefficient W2 (t) The reconstruction of w can be assumed to be obtained from the quantized non-zero coefficients of w3. T can be normalized so that W2 (0) =W2, where W2 is the matrix of combination coefficients reported by the PMI report.

[0242] Fig. 9 The exemplary block diagram shows how to combine wideband TRS-based time / Doppler domain reporting with FeType-II port selection CSI reporting. Figure 7 The broadband case is different in that the broadband coefficients apply to W f One or two FD basis components, depending on the gNB configuration.

[0243] Fig. 9 The exemplary block diagram shows how to measure and report the TRS-based time / Doppler domain for each (e.g., each) FD basis component separately and how to combine it with eType-IIPMI. In this case, the M FD basis components (W) selected in the traditional PMI calculation f) can be applied to the N4×N3 matrix W of TRS measurement TRS , to obtain an N4×M time measurement matrix W for at least one (eg, each) of the M components T . (Then) the UE can convert the D DD basis components (W D ), D≤N4, applied to matrix W T , to obtain a compressed representation of the time domain measurements in the D×M matrix W3. (t) The reconstruction formula of Figure 7 The reconstruction formula is similar to , except that a different time variation is applied to each of the M columns of W2 reported in the PMI.

[0244] Fig.10 Another exemplary block diagram shows how to measure and report different time / Doppler domains for each (e.g., each) SD base component and FD base component, and how to combine it with eType-IIPMI. In this case, the UE can Get N4 PMIs, corresponding to the precoder Then, the UE can D Each of the D basis vectors is applied to the 2L×M combination coefficients W2 (t) N4 matrices, and obtain D matrices W3 with d = 0, 1, ..., D-1 (d) .time The precoder matrix at can be expressed as follows, for example:

[0245]

[0246] Similarly, by changing W D The elements in row t and column d are represented by in(·) * Denoting the complex conjugate, the precoder matrix at time t can be written, for example, as follows:

[0247]

[0248] If the UE is equipped with multiple receive antennas, N rx >1, the same or different TRS-based time / Doppler domain quantities may be reported for each layer (e.g., each layer) in the n reporting layers. If the time variation measured for each layer is different, the UE may implement a time domain variable of length N. rx The same right singular vectors of are applied to N rxTRS measurements, the right singular vectors are obtained from the SVD or EVD in the CSI-RS based PMI calculation and used for layer calculation. The i-th right singular vector may contain combining coefficients, such as once applied to the receive antenna port, the combining coefficients may produce the corresponding i-th left singular vector associated with the i-th layer of the precoder matrix.

[0249] In the above and other exemplary embodiments, the DD base component (W) applied to N4 TRS measurement occasions D ) can be configured, for example, from a DFT-based or DCT (Discrete Cosine Transform)-based codebook. The DCT transform can be used to sample the Doppler spectrum, which can bring higher accuracy of the time-related representation at the edges. When compression is performed by DFT transform, these edge samples may be most affected by reconstruction errors because of the discontinuity of the signal to be compressed when it is extended by periodicity. Because DCT eliminates this discontinuity by symmetrically extending the signal and applying DFT to a signal of double length, DCT can provide a solution to this problem. Another advantage of DCT compression over DFT compression may be that the power of the compressed signal samples decreases with the Doppler component index. Therefore, the UE may not need to feed back the DD basis component (W D ). Instead, the gNB may configure the UE to determine (e.g., calculate) the first D components. Using a DCT-based Doppler component may save feedback overhead compared to a DCT-based codebook.

[0250] For a DCT-based codebook, the dth codebook element can be represented by the vector Given, its entries can be defined as:

[0251]

[0252] For a DFT-based precoder, the codebook entry can be defined as:

[0253]

[0254] The index t may be associated with the time domain, while d may be associated with the transformed Doppler domain.

[0255] The following provides an example of how to represent the time variation of the precoder matrix as a function of the traditional PMI report and the new time and / or Doppler domain information. Fig.10The exemplary reconstruction formula of is extended to an example. Similar formulas may be obtained for other possible embodiments. For example, let D be the number of DD components that the UE is configured to measure, D≤N4, and let f be the FD component index, f=0,...,M-1. It may be assumed that the M FD components are universal across layers, for example, as in the port selection codebook in Release 17. However, if the layer is specific, it may be necessary to determine (e.g., calculate) the DD combining coefficients for the union of the FD components selected across all reporting layers. For layer l, the magnitude of the combining coefficients associated with the D TD components may be indicated by:

[0256] q l =[q l，0 …q l,D-1 "

[0257] q l，d =[q l，0，d …q l,M-1，d ]

[0258] And their phases can be expressed as follows:

[0259] ψ l =[[ψ l，0 …ψ l，D-1 ]

[0260] ψ l，d =[ψ l，0，d …ψ l，M-1,d ].

[0261] For layer l, SD component i and FD component f, the amplitude and phase of the non-zero coefficients associated with the SD-FD basis component pair of the conventional CSI can be represented by p l，i，f and For subbands s = 0, ..., N3-1, and layers l = 1, ..., ν, the precoder expression at time t = 0, 1, ..., N4-1 is It can be extended as follows, where for i=0,…,L, represents the selected SD basis component, with size 2N1N2×1, for f=0,…,M-1, is the sth element of the fth selected FD basis component:

[0262]

[0263]

[0264] With respect to CQI calculation, the UE may be configured to determine (e.g., calculate) the CQI under the following assumptions: assuming that the downlink transmission occurs over a length of time period, and so that for example The precoder for subband s and layer l is applied at

[0265] As a further exemplary embodiment, a method is disclosed for measuring the temporal variation of a channel from a TRS signal, reporting corresponding channel state information, and using the information to determine the temporal variation of non-zero combining coefficients of a conventional Type-I or Type-I IPMI. The TRS temporal measurements may be reported, for example, as temporal correlations at predetermined time lags, or as transform coefficients associated with a set of basis components obtained from a codebook. Maximum temporal correlation lag It can be determined, for example, by the maximum time interval of the measured TRS resources, and the time unit T can correspond to the fraction T = t1, where N4 is the codebook dimension and T is the symbol duration T sym For example, a codebook configured for compressing time correlation may be formed, for example, from a discrete cosine transform basis.

[0266] Fig.11 is a schematic block diagram of an apparatus 1000 according to an exemplary aspect, which may, for example, represent one of the apparatuses 101 , 102 .

[0267] The apparatus 1000 comprises a processor 1001 , a program memory 1002 , a working memory or main memory 1003 , a data memory, communication interface(s) 1004 , and an optional user interface 1005 .

[0268] The apparatus 1000 may be configured to execute and / or control or include corresponding components (at least one of 1001 to 1005) for executing and / or controlling the method according to the first and / or second exemplary aspects, for example. The apparatus 1000 may also constitute an apparatus including at least one processor (1001) and at least one memory (1002), at least one memory including computer program code, at least one memory and computer program code configured to, together with at least one processor, enable the apparatus, for example, the apparatus 1000 to at least execute and / or control the method according to the first exemplary aspect.

[0269] The processor 1001 may also control, for example, the memories 1002 to 1003 , the communication interface(s) 1004 , and an optional user interface 1005 .

[0270] The processor 1001 may, for example, execute a computer program code stored in a program memory 1002, which may, for example, represent a computer-readable storage medium comprising a program code, which, when executed by the processor 1001, causes the processor 1001 to perform a method according to the first and / or second exemplary aspect.

[0271] Processor 1001 (and any other processors mentioned in this specification) can be any suitable type of processor. Processor 1001 may include, but is not limited to, one or more microprocessors, one or more processors with one or more digital signal processors, one or more processors without (multiple) digital signal processors, one or more special-purpose computer chips, one or more field programmable gate arrays (FPGAs), one or more controllers, one or more application-specific integrated circuits (ASICs), or one or more computers. The relevant structure / hardware has been programmed in a manner to perform the described functions. Processor 1001 may, for example, be an application processor running an operating system.

[0272] A program memory 1002 may also be included in the processor 1001. The memory may, for example, be fixedly connected to the processor 1001, or may be at least partially removable from the processor 1001, for example in the form of a memory card or a memory stick. The program memory 1002 may, for example, be a non-volatile memory. For example, it may be a flash memory (or a portion thereof), or any one of a ROM, PROM, EPROM and EEPROM memory (or a portion thereof), or a hard disk (or a portion thereof), to name just a few examples. The program memory 1002 may also include an operating system for the processor 1001. The program memory 1002 may also include firmware for the device 1000.

[0273] The apparatus 1000 comprises a working memory 1003, for example comprising a working memory 1003 in the form of a volatile memory. For example, the working memory 1003 may be a random access memory (RAM), or a dynamic RAM (DRAM), to give just a few non-limiting examples. For example, it may be used by the processor 1001 when executing an operating system and / or a computer program.

[0274] The data storage may be, for example, a non-volatile memory. For example, it may be a flash memory (or a portion thereof), or any one of a ROM, a PROM, an EPROM, and an EEPROM memory (or a portion thereof), or a hard disk (or a portion thereof), to name a few examples. The data storage may, for example, store one or more pieces of information, such as measurements of acquired CSI-RS and / or TRS.

[0275] The communication interface(s) 1004 enable the apparatus 1000 to communicate with other entities. The communication interface(s) 1004 may, for example, include: a wireless interface (e.g., a cellular radio communication interface and / or a WLAN interface), and / or a wired interface (e.g., an IP-based interface), for example, to communicate with entities via the Internet. The communication interface(s) may enable the apparatus 1000 to communicate with other entities (e.g., one or more entities included by a mobile communication network).

[0276] The user interface 1005 is optional and may include: a display for displaying information to a user, and / or an input device (eg, a keyboard, keypad, touch pad, mouse, etc.) for receiving information from a user.

[0277] Some or all of the components of the apparatus 1000 may be connected, for example, via a bus. Some or all of the components of the apparatus 1000 may be combined into one or more modules, for example.

[0278] The disclosed exemplary aspects may allow for time domain channel tracking, and / or adding time domain correlation and / or Doppler domain information to conventional Type-I / eType-I ICSI reports, e.g., without requiring measurements to be made on multiple CSI-RS opportunities, and without requiring changes to combining coefficients in conventional CSI reporting. Various exemplary embodiments may enable improved signaling.

[0279] The following embodiments should also be considered disclosed:

[0280] Embodiment 1:

[0281] A method, such as a method performed by a user equipment, comprises:

[0282] -Acquire time domain and / or Doppler domain information based on measuring the time variation of the channel from the tracking reference signal TRS;

[0283] - Reporting time domain and / or Doppler domain information, and channel state information CSI, wherein the CSI is obtained by measuring a CSI reference signal CSI-RS.

[0284] Embodiment 2:

[0285] The method according to embodiment 1 further includes:

[0286] - Obtaining a first configuration to report Nt time-domain correlation values ​​calculated from the TRS, and / or to report non-zero coefficients associated with D Doppler-domain codebook components, D≤Nt, where Nt and D are integers.

[0287] Embodiment 3:

[0288] The method according to embodiment 2 further includes:

[0289] - Obtaining a second configuration to provide TRS-based time domain and / or Doppler domain measurements in a wideband format or in a sub-band format.

[0290] Embodiment 4:

[0291] According to the method of embodiment 2 or 3, the Doppler domain codebook component includes: a discrete cosine transform DCT-based and / or DFT-based codebook component.

[0292] Embodiment 5:

[0293] According to the method of any one of embodiments 1 to 4, the time domain and / or Doppler domain information and the CSI are reported to the network node respectively.

[0294] Embodiment 6:

[0295] The method according to any one of embodiments 1 to 5, wherein TRS-based time domain and / or Doppler domain information is reported for each layer in the precoder matrix indicator reported in the CSI.

[0296] Embodiment 7:

[0297] A method, such as a method performed by a network node, comprises:

[0298] - receiving time domain and / or Doppler domain information, and at least one channel state information CSI;

[0299] - Reconstruct the time domain function based on the time domain and / or Doppler domain information and the CSI-based precoder matrix.

[0300] Embodiment 8:

[0301] The method according to embodiment 7 further includes:

[0302] - Providing a first configuration (e.g., configuring; e.g., by a network node, e.g., to a user equipment) to report Nt time-domain correlation values ​​calculated from a TRS, and / or to report non-zero coefficients associated with D Doppler-domain codebook components, D≤Nt, where Nt and D are integers.

[0303] Embodiment 9:

[0304] The method according to embodiment 8 further includes:

[0305] A second configuration is provided (eg, configured; eg, by a network node, eg, to a user equipment) to provide TRS-based time domain and / or Doppler domain measurements in a wideband form or in a sub-band form.

[0306] Embodiment 10:

[0307] According to the method of embodiment 8 or 9, the Doppler domain codebook component includes: a discrete cosine transform DCT-based and / or DFT-based codebook component.

[0308] Embodiment 11:

[0309] According to the method of any one of embodiments 7 to 10, time domain and / or Doppler domain information, and CSI are acquired separately (for example, from a user equipment).

[0310] Embodiment 12:

[0311] According to the method of any one of embodiments 7 to 11, the TRS-based time domain and / or Doppler domain information is obtained for each layer of the precoder matrix indicator of the CSI (for example, obtained from the user equipment).

[0312] Embodiment 13:

[0313] An apparatus comprising components for:

[0314] - based on the measured time variations, obtaining time domain and / or Doppler domain information;

[0315] - Reporting time domain and / or Doppler domain information, and at least one channel state information CSI, wherein the CSI is obtained by measuring a CSI reference signal CSI-RS.

[0316] Embodiment 14:

[0317] According to the device of embodiment 13, reporting time domain and / or Doppler domain information includes: reporting Nt time domain correlation values ​​calculated from TRS, and / or reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers.

[0318] Embodiment 15:

[0319] According to the apparatus of the embodiment, reporting of time domain and / or Doppler domain information is performed in a wideband form or a sub-band form.

[0320] Embodiment 16:

[0321] An apparatus according to embodiment 14 or 15, wherein reporting time domain and / or Doppler domain information comprises: reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, wherein Nt and D are integers, wherein the Doppler domain codebook components comprise: codebook components based on discrete cosine transform DCT and / or DFT.

[0322] Embodiment 17:

[0323] According to the device of any one of embodiments 13 to 16, time domain and / or Doppler domain information, and CSI are reported separately.

[0324] Embodiment 18:

[0325] The apparatus according to any one of embodiments 13 to 17, wherein reporting time domain and / or Doppler domain information is performed for each layer in the precoder matrix indicator reported in the CSI.

[0326] Embodiment 19:

[0327] The device according to any one of embodiments 13 to 18, further comprising means for:

[0328] - Obtain at least one CSI reference signal CSI-RS for obtaining at least one CSI, and obtain at least one tracking reference signal TRS;

[0329] -Measure the time variation of the channel based on TRS.

[0330] Embodiment 20:

[0331] The apparatus according to any one of embodiments 13 to 19, wherein the apparatus is a user equipment.

[0332] Embodiment 21:

[0333] An apparatus comprising components for:

[0334] - Obtaining time domain and / or Doppler domain information, and at least one channel state information CSI;

[0335] - Reconstruct the time domain function based on the time domain and / or Doppler domain information and the CSI-based precoder matrix.

[0336] Embodiment 22:

[0337] The apparatus according to embodiment 21 further comprises components for the following operations:

[0338] - providing a first configuration to a further apparatus for reporting Nt time domain correlation values ​​calculated from a tracking reference signal TRS and / or for reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers.

[0339] Embodiment 23:

[0340] The apparatus according to embodiment 22 further comprises components for the following operations:

[0341] - Providing a second configuration to a further device to provide TRS based time domain and / or Doppler domain measurements in a wideband format or in a sub-band format.

[0342] Embodiment 24:

[0343] The apparatus according to embodiment 22 or 23, wherein the Doppler domain codebook component comprises: a discrete cosine transform DCT-based and / or DFT-based codebook component.

[0344] Embodiment 25:

[0345] An apparatus according to any one of embodiments 21 to 24, wherein time domain and / or Doppler domain information, and CSI are acquired separately.

[0346] Embodiment 26:

[0347] The apparatus according to any one of embodiments 21 to 25, wherein TRS-based time domain and / or Doppler domain information is obtained for each layer of the precoder matrix indicator of the CSI.

[0348] Embodiment 27:

[0349] The apparatus according to any one of embodiments 21 to 26, wherein the apparatus is a Radio Access Network RAN ​​node of a mobile communication network.

[0350] Embodiment 28:

[0351] A system comprising:

[0352] - at least one device according to any one of embodiments 13 to 20; and

[0353] - The device of any one of embodiments 21 to 27.

[0354] Embodiment 29:

[0355] A computer-readable medium includes program instructions configured to execute and / or control, or includes corresponding components for executing and / or controlling the method of any one of embodiments 1 to 6.

[0356] Embodiment 30:

[0357] A computer-readable medium comprising program instructions configured to execute and / or control, or comprising corresponding components for executing and / or controlling the method of any one of Embodiments 7 to 12.

[0358] Embodiment 31:

[0359] A tangible storage medium includes program instructions configured to execute and / or control, or includes corresponding components for executing and / or controlling the method of any one of embodiments 1 to 6 and / or 7 to 12.

[0360] In this specification, any connection presented in the described embodiments should be understood as the components involved being coupled in an operational manner. Therefore, the connection may be a direct or indirect connection with any number or combination of intermediate elements, and there may only be a functional relationship between the components.

[0361] In addition, any method, process, and action described or illustrated herein may be implemented using executable instructions in a general or special purpose processor and stored on a computer-readable storage medium (e.g., disk, memory, etc.) for execution by such a processor. References to "computer-readable storage medium" should be understood to cover special purpose circuits such as FPGAs, ASICs, signal processing devices, and other devices.

[0362] The expression "A and / or B" is considered to include any of the following three situations: (i) A, (ii) B, (iii) A and B. In addition, the article "a" should not be understood as "an", that is, the use of "an element" does not exclude the presence of additional elements. The term "comprising" should be understood in an open sense, that is, in a way that the object of "comprising element A" can include additional elements in addition to element A. In addition, the term "comprising" can be limited to "consisting of", that is, consisting of only the specified elements.

[0363] It should be understood that all presented embodiments are exemplary only, and any feature presented for a particular example embodiment may be used alone with any aspect, or in combination with any feature presented for the same or another particular example embodiment, and / or in combination with any other features not mentioned. In particular, the example embodiments presented in this specification should also be understood to be disclosed in all possible combinations with each other, as long as they are technically reasonable and the example embodiments are not alternative aspects of each other. It should also be understood that any feature presented for an example embodiment in a particular category (method / device / computer program / system) may also be used in a corresponding manner in any other category of example embodiments. It should also be understood that the presence of a feature in the presented example embodiments does not necessarily mean that the feature forms a necessary feature and cannot be omitted or replaced.

[0364] It is not mandatory that the specification of a feature includes at least one of the features listed subsequently, since the feature includes all the features listed subsequently or includes at least one of a plurality of features listed subsequently. Furthermore, the listed features may be selected in any combination or only one of the listed features may be selected. Specific combinations of all the features listed subsequently are also conceivable. Furthermore, a plurality of or only one of the listed features may be employed.

[0365] The order of all the above method steps is not mandatory, and alternative orders may also be adopted. Nevertheless, the specific order of the method steps exemplarily shown in the figures should be considered as a possible order of the method steps of the corresponding embodiments described by the corresponding figures.

[0366] The subject matter has been described above by way of example embodiments. It should be noted that there are alternatives and variations that are obvious to those skilled in the art and may be implemented without departing from the scope of the appended claims.

Claims

1. A method comprising: -Acquire time domain and / or Doppler domain information based on measuring the time variation of the channel from the tracking reference signal TRS; - reporting the time domain and / or Doppler domain information, and channel state information CSI, wherein the CSI is obtained by measuring a CSI reference signal CSI-RS.

2. The method according to claim 1, further comprising: - obtaining a first configuration to report Nt time domain correlation values ​​calculated from the TRS, and / or to report non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers.

3. The method according to claim 2, further comprising: - Obtaining a second configuration to provide TRS-based time domain and / or Doppler domain measurements in a wideband format or in a sub-band format.

4. The method according to claim 2 or 3, wherein the Doppler domain codebook component comprises: Discrete Cosine Transform DCT based and / or DFT based codebook components.

5. The method according to any one of claims 1 to 4, wherein the time domain and / or Doppler domain information, and the CSI are reported to a network node respectively.

6. The method according to any one of claims 1 to 5, wherein the time domain and / or Doppler domain information based on TRS is reported for each layer in a precoder matrix indicator reported in the CSI.

7. A method comprising: - receiving time domain and / or Doppler domain information, and at least one channel state information CSI; - Reconstructing a time domain function based on the time domain and / or Doppler domain information and a precoder matrix based on the CSI.

8. The method according to claim 7, further comprising: - providing a first configuration for reporting Nt time domain correlation values ​​calculated from the TRS, and / or reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers.

9. The method according to claim 8, further comprising: - Providing a second configuration to provide TRS based time domain and / or Doppler domain measurements in a wideband form or in a sub-band form.

10. The method according to claim 8 or 9, wherein the Doppler domain codebook component comprises: Discrete Cosine Transform DCT based and / or DFT based codebook components.

11. The method according to any one of claims 7 to 10, wherein the time domain and / or Doppler domain information, and the CSI are acquired separately.

12. The method according to any one of claims 7 to 11, wherein the time domain and / or Doppler domain information based on TRS is obtained for each layer in a precoder matrix indicator of the CSI.

13. An apparatus comprising at least one processor and at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the apparatus to at least perform: - based on the measured time variations, obtaining time domain and / or Doppler domain information; - reporting the time domain and / or Doppler domain information, and the at least one channel state information CSI, wherein the CSI is obtained by measuring a CSI reference signal CSI-RS.

14. The apparatus according to claim 13, wherein the reporting of the time domain and / or Doppler domain information comprises: Reporting Nt time domain correlation values ​​calculated from the TRS, and / or reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers. 15 . The apparatus according to claim 14 , wherein the reporting of the time domain and / or Doppler domain information is performed in a wideband form or a sub-band form.

16. The apparatus according to claim 14 or 15, wherein the reporting of the time domain and / or Doppler domain information comprises: Non-zero coefficients associated with D Doppler domain codebook components are reported, D≤Nt, where Nt and D are integers, wherein the Doppler domain codebook components include: discrete cosine transform DCT-based and / or DFT-based codebook components.

17. The apparatus according to any one of claims 13 to 16, wherein the time domain and / or Doppler domain information, and the CSI are reported separately.

18. The apparatus according to any one of claims 13 to 17, wherein the reporting of the time domain and / or Doppler domain information is performed for each layer in a precoder matrix indicator reported in the CSI.

19. An apparatus comprising at least one processor and at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the apparatus to at least perform: - Obtaining time domain and / or Doppler domain information, and at least one channel state information CSI; - Reconstructing a time domain function based on the time domain and / or Doppler domain information and a precoder matrix based on the CSI.

20. The apparatus of claim 19, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: - providing a first configuration to a further apparatus for reporting Nt time domain correlation values ​​calculated from a tracking reference signal TRS and / or for reporting non-zero coefficients associated with D Doppler domain codebook components, D≤Nt, where Nt and D are integers.

21. The apparatus of claim 20, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform: - providing a second configuration to the further device to provide TRS based time domain and / or Doppler domain measurements in a wideband format or in a sub-band format.

22. The apparatus according to claim 20 or 21, wherein the Doppler domain codebook component comprises: Discrete Cosine Transform DCT based and / or DFT based codebook components.

23. The apparatus according to any one of claims 19 to 22, wherein the time domain and / or Doppler domain information, and the CSI are acquired separately.

24. The apparatus according to any one of claims 19 to 23, wherein the time domain and / or Doppler domain information based on TRS is obtained for each layer in a precoder matrix indicator of the CSI.

25. A system comprising at least two devices, wherein the at least two devices together perform the method according to any one of claims 1 to 6, and / or 7 to 12.

26. A computer program which, when executed by a processor of an apparatus, causes the apparatus to perform a method according to any one of claims 1 to 6, and / or 7 to 12.

27. A tangible and / or non-transitory storage medium comprising instructions stored thereon for executing the method according to any one of claims 1 to 6, and / or 7 to 12.

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