WO2021032265A1

WO2021032265A1 - Incremental frequency domain feedback for type ii channel state information

Info

Publication number: WO2021032265A1
Application number: PCT/EP2019/072011
Authority: WO
Inventors: Rana Ahmed Salem; Salah HAJRI; Marco MASO
Original assignee: Nokia Technologies Oy
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2021-02-25

Abstract

An example method, apparatus, and computer-readable storage medium are provided for an efficient inter-system direct forwarding procedure. In an example implementation, the method may include performing, by a user equipment (UE), channel estimation of a downlink reference signal received from a network node, the channel estimation represented by a compressed linear combination coefficient (LCC) matrix, a set of spatial domain beams, and a set of frequency domain basis vectors. The method may further include generating, by the user equipment (UE), a plurality of partitions, a partition of the plurality of partitions being generated based on a combination of one or more of: linear combination coefficients (LCCs) of the compressed linear combination coefficient (LCC) matrix, a bitmap which indicates whether a corresponding linear combination coefficient (LCC) is a non-zero or zero linear combination coefficient (LCC), and a frequency domain (FD) component matrix; and transmitting, by the user equipment (UE), a first partition of the generated plurality of partitions to the network node.

Description

INCREMENTAL FREQUENCY DOMAIN FEEDBACK FOR TYPE II CHANNEL STATE INFORMATION

TECHNICAL FIELD

[0001] This description relates to wireless communications, and in particular, to Type II channel state information (CSI) feedback.

BACKGROUND

[0002] A communication system may be a facility that enables communication between two or more nodes or devices, such as fixed or mobile communication devices. Signals can be carried on wired or wireless carriers.

[0003] An example of a cellular communication system is an architecture that is being standardized by the 3rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP or Evolved Node B (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments.

[0004] 5G New Radio (NR) is part of a continued mobile broadband evolution process to meet the requirements of 5G, similar to earlier evolution of 3G & 4G wireless networks. In addition, 5G is also targeted at the new emerging use cases in addition to mobile broadband.

A goal of 5G is to provide significant improvement in wireless performance, which may include new levels of data rate, latency, reliability, and security. 5G NR may also scale to efficiently connect the massive Internet of Things (IoT), and may offer new types of mission- critical services. Ultra-reliable and low-latency communications (URLLC) devices may require high reliability and very low latency.

SUMMARY

[0005] An example method, apparatus, and computer-readable storage medium are provided for an incremental frequency domain feedback mechanism for Type II channel state information (CSI). In an example implementation, the method may include performing, by a user equipment (UE), channel estimation of a downlink reference signal received from a network node, the channel estimation represented by a compressed linear combination coefficient (FCC) matrix, a set of spatial domain beams, and a set of frequency domain basis vectors. The method may further include generating, by the user equipment (UE), a plurality of partitions, a partition of the plurality of partitions being generated based on a combination of one or more of: linear combination coefficients (FCCs) of the compressed linear combination coefficient (FCC) matrix, a bitmap which indicates whether a corresponding linear combination coefficient (FCC) is a non-zero or zero linear combination coefficient (FCC), and a frequency domain (FD) component matrix; and transmitting, by the user equipment (UE), a first partition of the generated plurality of partitions to the network node.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a block diagram of a wireless network according to an example implementation.

[0007] FIG. 2 is a flow chart illustrating an incremental frequency domain feedback mechanism for Type II channel state information (CSI), according to at least one example implementation.

[0008] FIG. 3 illustrates an example of PMI partitioning along FCC matrix columns, according to at least one example implementation.

[0009] FIG. 4 illustrates feedback schemes, according to example implementations.

[0010] FIG. 5A illustrates an example implementation of Scheme A, according to at least one example implementation.

[0011] FIG. 5B illustrates an example implementation of Scheme B, according to at least one example implementation.

[0012] FIG. 6A illustrates an example of joint space and frequency incremental reporting mechanism, according to at least one example implementation.

[0013] FIG. 6B illustrates an additional example with non-contiguous partitions, according to at least one more example implementation.

[0014] FIG. 7 is a block diagram of a node or wireless station (e.g., base station/access point or mobile station/user device/UE), according to an example implementation.

DETAIFED DESCRIPTION

[0015] FIG. 1 is a block diagram of a wireless network 130 according to an example implementation. In the wireless network 130 of FIG. 1, user devices (UDs) 131, 132, 133 and 135, which may also be referred to as mobile stations (MSs) or user equipment (UEs), may be connected (and in communication) with a base station (BS) 134, which may also be referred to as an access point (AP), an enhanced Node B (eNB) or a network node. At least part of the functionalities of an access point (AP), base station (BS) or (e)Node B (eNB) may also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remote radio head. BS (or AP) 134 provides wireless coverage within a cell 136, including to user devices 131, 132, 133 and 135. Although only four user devices are shown as being connected or attached to BS 134, any number of user devices may be provided. BS 134 is also connected to a core network 150 via a SI interface 151. This is merely one simple example of a wireless network, and others may be used.

[0016] A user device (user terminal, user equipment (UE)) may refer to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, and a multimedia device, as examples, or any other wireless device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network.

[0017] In LTE (as an example), core network 150 may be referred to as Evolved Packet Core (EPC), which may include a mobility management entity (MME) which may handle or assist with mobility/handover of user devices between BSs, one or more gateways that may forward data and control signals between the BSs and packet data networks or the Internet, and other control functions or blocks.

[0018] In addition, by way of illustrative example, the various example implementations or techniques described herein may be applied to various types of user devices or data service types, or may apply to user devices that may have multiple applications running thereon that may be of different data service types. New Radio (5G) development may support a number of different applications or a number of different data service types, such as for example: machine type communications (MTC), enhanced machine type communication (eMTC), Internet of Things (IoT), and/or narrowband IoT user devices, enhanced mobile broadband (eMBB), and ultra-reliable and low-latency communications (URLLC).

[0019] IoT may refer to an ever-growing group of objects that may have Internet or network connectivity, so that these objects may send information to and receive information from other network devices. For example, many sensor type applications or devices may monitor a physical condition or a status, and may send a report to a server or other network device, e.g., when an event occurs. Machine Type Communications (MTC or machine to machine communications) may, for example, be characterized by fully automatic data generation, exchange, processing and actuation among intelligent machines, with or without intervention of humans. Enhanced mobile broadband (eMBB) may support much higher data rates than currently available in LTE.

[0020] Ultra-reliable and low-latency communications (URLLC) is a new data service type, or new usage scenario, which may be supported for New Radio (5G) systems. This enables emerging new applications and services, such as industrial automations, autonomous driving, vehicular safety, e-health services, and so on. 3GPP targets in providing up to e.g., 1 ms U-Plane (user/data plane) latency connectivity with l-le-5 reliability, by way of an illustrative example. Thus, for example, URLLC user devices/UEs may require a significantly lower block error rate than other types of user devices/UEs as well as low latency. Thus, for example, a URLLC UE (or URLLC application on a UE) may require much shorter latency, as compared to an eMBB UE (or an eMBB application running on a UE).

[0021] The various example implementations may be applied to a wide variety of wireless technologies or wireless networks, such as LTE, LTE-A, 5G, IoT, MTC, eMTC, eMBB, URLLC, etc., or any other wireless network or wireless technology. These example networks, technologies or data service types are provided only as illustrative examples. Multiple Input, Multiple Output (MIMO) may refer to a technique for increasing the capacity of a radio link using multiple transmit and receive antennas to exploit multipath propagation. MIMO may include the use of multiple antennas at the transmitter and/or the receiver.

MIMO may include a multi-dimensional approach that transmits and receives two or more unique data streams through one radio channel. For example, MIMO may refer to a technique for sending and receiving more than one data signal simultaneously over the same radio channel by exploiting multipath propagation. According to an illustrative example, multi-user multiple input, multiple output (multi-user MIMIO, or MU-MIMO) enhances MIMO technology by allowing a base station (BS) or other wireless node to simultaneously transmit or receive multiple streams to different user devices or UEs, which may include simultaneously transmitting a first stream to a first UE, and a second stream to a second UE, via a same (or common or shared) set of physical resource blocks (PRBs) (e.g., where each PRB may include a set of time- frequency resources).

[0022] Also, a BS may use precoding to transmit data to a UE (based on a precoder matrix or precoder vector for the UE). For example, a UE may receive reference signals or pilot signals, and may determine a quantized version of a DL channel estimate, and then provide the BS with an indication of the quantized DL channel estimate. The BS may determine a precoder matrix based on the quantized channel estimate, where the precoder matrix may be used to focus or direct transmitted signal energy in the best channel direction for the UE. Also, each UE may use a decoder matrix may be determined, e.g., where the UE may receive reference signals from the BS, determine a channel estimate of the DL channel, and then determine a decoder matrix for the DL channel based on the DL channel estimate. For example, a precoder matrix may indicate antenna weights (e.g., an amplitude/gain and phase for each weight) to be applied to an antenna array of a transmitting wireless device. Likewise, a decoder matrix may indicate antenna weights (e.g., an amplitude/gain and phase for each weight) to be applied to an antenna array of a receiving wireless device. This applies to UL as well when a UE is transmitting data to a BS.

[0023] For example, according to an example aspect, a receiving wireless user device may determine a precoder matrix using Interference Rejection Combining (IRC) in which the user device may receive reference signals (or other signals) from a number of BSs (e.g., and may measure a signal strength, signal power, or other signal parameter for a signal received from each BS), and may generate a decoder matrix that may suppress or reduce signals from one or more interferers (or interfering cells or BSs), e.g., by providing a null (or very low antenna gain) in the direction of the interfering signal, in order to increase a signal-to interference plus noise ratio (SINR) of a desired signal. In order to reduce the overall interference from a number of different interferers, a receiver may use, for example, a Linear Minimum Mean Square Error Interference Rejection Combining (LMMSE-IRC) receiver to determine a decoding matrix. The IRC receiver and LMMSE-IRC receiver are merely examples, and other types of receivers or techniques may be used to determine a decoder matrix. After the decoder matrix has been determined, the receiving UE/user device may apply antenna weights (e.g., each antenna weight including amplitude and phase) to a plurality of antennas at the receiving UE or device based on the decoder matrix. Similarly, a precoder matrix may include antenna weights that may be applied to antennas of a transmitting wireless device or node. This applies to a receiving BS as well.

[0024] The significant gains promised by massive input massive output (MIMO) systems in 5G and beyond are conditioned on the availability of accurate channel state information (CSI)/precoding matrix indicator (PMI) at a gNB. In a frequency division duplex system (FDD), a user equipment (UE) has to provide feedback regarding the downlink reference signal to the gNB due to the absence of channel reciprocity.

[0025] In 5G and beyond, where a user equipment (UE) is connected to multiple transmission reception points (TRPs) each TRP with its own uplink (UL) CSI feedback, the UL overhead from CSI feedback can consumes a lot of UL resources and/or can become a bottleneck on the UL.

[0026] In addition, physical uplink control channel (PUCCH)/physical uplink shared channel (PUSCH) based CSI reporting containers may be too small to fit the entire CSI report payload, especially for wide bandwidth parts (BWPs). However, under such situations, special omission rules are applied, and parts of the CSI report or entire reports are dropped. However, this will degrade the accuracy of fed back PMIs and would penalize UEs with high CSI report indices.

[0027] UCI omission - For PUSCH-based reporting, when the CSI container is too small to fit the entire CSI payload, special omission rules apply where partial CSI Part 2 payload may be omitted. For example, in Release 15, in case CSI Part 2 comprises CSI from multiple CSI reports, CSI repots with lower CSI Report Index has higher priority. In Release 15, within a CSI Report, subband CSI with even subbands has higher priority than odd subbands. The idea here is that with information on the CSI on the even subbands, the gNB can interpolate the CSI to obtain the missing CSI on the odd subbands.

[0028] In Release 16 NR type II CSI, the CSI feedback is not sent per subband as was the case with Release 15 feeding back W_2 matrix, instead the FC coefficients in the FD are sent hence dropping the even subbands is no longer an option as was the case in Release 15.

[0029] Therefore, in order to ensure the scalability of the system, further effort needs to be considered to efficiently compress the CSI feedback, exploit all sources of correlation inside the CSI feedback information and manage CSI reporting payload over time.

[0030] The present disclosure describes a proposal which includes an incremental reporting scheme for Rel. 16 type II codebook, for example, for the compressed FCC matrix In some implementations, for example,

may be partitioned into a plurality of partitions and at each time instant a different part of , e.g., a different partition may be fed

back (e.g., sent, transmitted, etc.) to the network node (e.g., radio access network node) while the previously sent partition is assumed constant (e.g., no change). In other words, an incremental approach may be applied to FC coefficients on the basis of FD components (e.g., one dimensional partitioning along the columns) or on the basis of SD beams and FD components jointly (e.g., two-dimensional partitioning).

[0031] In some implementations, for example, index re-mapping may need a special structure for wherein the earlier (e.g., first) FD components carry more relevant information. In addition, as the network node (e.g., gNB) is aware (in advance) of the order of priority of the components inside , there is no need for additional feedback from the UE (to indicate which components have higher priority). Therefore, a fixed schedule may be agreed upon by UE and gNB for updating the different partitions inside Moreover, even

without the index re-mapping at the UE, discrete Fourier transform (DFT) compression tends to concentrate energy of correlated signals into low pass components and therefore a fixed schedule may still be derived even without the Rel. 16 agreement on strongest coefficient indicator (SCI).

[0032] In some implementations, for example, if the strongest FD component is not at position 0, the UE may send (feedback) parts of the CSI report starting from the one conveying the highest LCC amplitudes, and feedback the parts in a decreasing order of average or total LCC amplitude at each time instant. In such a scenario, an additional indicator may be needed to notify the gNB about the FD component that contains the strongest coefficient. In some implementations, for example, efficient CSI omission rules and payload management procedure are described such that CSI dropping is minimized or subsequent information loss is reduced. It should be noted that in both approaches, no error propagation occurs, because the information sent at time t doesn't depend on the information sent at time t-1.

[0033] The described proposal provides several benefits to provide accurate FD compressed type II CSI while (e.g., simultaneously) addressing the overhead bottleneck on the uplink.

[0034] FIG. 2 is a flow chart 200 illustrating an incremental frequency domain feedback mechanism 200 for Type II channel state information (CSI), according to at least one example implementation.

[0035] At block 210, a user equipment (UE) which may be same or similar to user device of FIG. 1, for example, user devices 131, 132, 133, and/or 135 of FIG.1, may perform channel estimation of a downlink reference signal received from a network node which may be same or similar to BS 134 of FIG. 1. In some implementations, for example, the channel estimation performed by the UE may be represented by a compressed linear combination coefficient (LCC) matrix (e.g., 310 of FIG. 3), a set of spatial domain (SD) beams, and a set of frequency domain basis vectors.

[0036] At block 220, the UE may generate a plurality of partitions. In some implementations, for example, a partition of the plurality of partitions may be generated based on a combination of one or more of linear combination coefficients (LCCs) of the compressed linear combination coefficient (LCC) matrix (222), a bitmap which indicates whether a corresponding linear combination coefficient (LCC) is a non-zero or zero linear combination coefficient (LCC) (224), and a frequency domain (FD) component matrix (226), as illustrated in detail in FIG. 3. In some implementations, for example, as illustrated in FIG. 3, the UE may generate three partitions, partitions 360, 370, and 380 based on a combination of LCC matrices (330, 332, and 334) and/or bitmap 340.

[0037] At block 230, the UE may transmit a first partition of the generated plurality of partitions to the network node. In some implementations, for example, the UE may transmit partition 0 (360) to the network node. As shown in FIG. 3, partition 0 (360) may include the strongest components. In addition, in some implementations, for example, as part of the incremental feedback mechanism, the UE may transmit a second partition, partition 1 (370) to the network node, and so on.

[0038] The above described proposal, for example: reduces impact of CSI aging due to constant feed of information (e.g., 4 ms delay between the reception of a CSI feedback instance and its use by the scheduler); provides flexibility to the UE so that it can prioritize the parts of the PMI that convey the largest amount of information; spreads CSI overhead over time so more UEs can be considered for scheduling which may improve multi-user (MU) multiplexing gain; and/or enables efficient CSI omission rules when PUSCH CSI containers are too small to fit the entire CSI payload.

[0039] In some implementations, for example, the sizes of the partitions, e.g., first partition, second partition, third partition, etc. may be selected based on sizes of scheduled physical uplink shared channel (PUSCH) or physical uplink control channel (PUCCH) resources as the partitions should fit the available resources.

[0040] In some implementations, for example, the UE may transmit updates for the first partition at a first time interval and/or the second partition at a second time interval, wherein the first time interval is same or different from the second time interval. In some more implementations, for example, wherein the first interval and/or second time interval are configured with different values for different layers. That is, different timers can be used for different partitions. For instance, the strongest FD components (partition #0) may remain steady for a longer time (relative to other FD components) and therefore they may be updated at a lower periodicity. Alternatively, partition(s) with lower indices may be considered as more important and may be updated at a higher periodicity. In other words, the timers and partitioning maybe designed differently for different layers (e.g., streams).

[0041] In some implementations, for example, the UE may receive channel state information (CSI) reports configuration information from the network node. The configuration information received from the network node may indicate frequency domain (FD) beams to be included in a particular channel state information (CSI) report partition. The UE, based on the configuration information received from the network node may generate channel state information (CSI) reports based and transmit the generated channel state information (CSI) reports to the network node.

[0042] In some implementations, for example, wherein the partitions are channel state information (CSI) report partitions, the configuration information received from the network node may indicate one or more of: a number of the partitions (for example, three partitions based on the example implementation in FIG. 3), sizes of the partitions; maximum number of non-zero linear combination coefficients and/or priorities for the partitions.

[0043] In some implementations, for example, the UE may determine that the component that is associated with the strongest linear coefficient is not at position zero and the UE may send an indicator (e.g., SCI is 331 for layer 0) to the network node identifying the component that is associated with the strongest linear combination coefficient.

[0044] As described below in reference to FIGs. 4-7, in some implementations, for example, the plurality of partitions may be generated based on: partitioning of the channel estimation jointly using incremental reporting of space and frequency components; non contiguous partitions.

[0045] In some implementations, for example, wherein a frequency domain (FD) component is a vector that is selected from a frequency domain basis, and each column of the linear combination coefficient (LCC) matrix being associated to a frequency domain (FD) component. In some implementations, for example, wherein the frequency domain (FD) component with a lower index value has higher priority. In some implementations, for example, wherein the plurality of partitions is prioritized according to indices of the corresponding FD components. In some implementations, for example, wherein the downlink reference signal is a channel state information-reference signal (CSI-RS). In some implementations, for example, determining that the component associated with the strongest linear combination coefficient is not at position zero; and sending an indicator to the network node identifying the component associated with the strongest linear combination coefficient. In some implementations, for example, the network node is a radio access network node.

[0046] Example implementation 1.1- In some implementations, for example, because of index re-mapping, it may be possible to devise a fixed schedule of priority at the gNB for the different parts of The schedule by which the partitions are fed back and the activation of

the scheduling feature can be either: a) fixed in the specification depending on the feedback parameters (feedback periodicity, N₃, feedback container size, etc.), or b) adaptively configured based on having a set of fixed scheduling options at UE and gNB, and UE/gNB to choose among them by signaling an index (e.g., in downlink control information). [0047] In another example implementation, the schedule may be configured by signaling the sizes of the respective partitions (e.g., number of columns) according to their order inside the W₂ matrix. In other words, only the partitions’ sizes need to be communicated between UE and gNB since the order of the partitions in the schedule is the same as their original order inside the FD matrices (

and bit-map).

[0048] The partitions may be of same or variable sizes. In some implementations, this may be considered in order to provide further flexibility to the gNB when scheduling PUSCH or PUCCH CSI feedback resources. The configuration of the schedule by which the partitions are fed back may be part of CSI-ReportConfig in RRC.

[0049] In an example implementation, a group of M_t FD columns inside

can be updated simultaneously, where 1 £ M_t < M . Each group of columns may be

referred to as a CSI feedback partition or a CSI Report partition. Each CSI feedback partition k may consist of 2-3 parts: or Parts of the CSI feedback within one

partition may be updated at different intervals (also referred to as timer), e.g. , updated

more frequently than Wf _t and b_t or alternatively W_{2 t} and b_t updated more ffequenctly than W_{f t}. For instance, different timers may be used for different partitions, as that the strongest FD components (partition #0) may remain steadier for a longer time and may be updated at a lower periodicity. Alternatively, partition(s) with lower indices may be considered more important and may be updated at a higher periodicity. It should be noted that the timers and partitioning may be designed differently for different layers (streams) and the UE may select the CSI partition based on the size of scheduled PUSCH or PUCCH CSI containers in order to reduce CSI dropping.

[0050] Example implementation 1.2 - In some implementations, for example, in a UCI omission rule for Rel.16 (or future releases), FD components with lower index may have higher priority than FD components of higher index in a UCI omission rule. That is, in case CSI Part 2 comprise CSI from multiple CSI reports, FD components in a CSI Report with lower indices may have higher priority than FD components with higher indices.

[0051] In an example implementation, in a UCI omission rule for Rel.16 (or future releases), some parts of the CSI feedback within 1 CSI partition may have higher priority than other parts of the CSI feedback within the CSI partition. For example, within a CSI Report partition, matrix of LC coefficients

has higher priority than bit-map vector b_t. It should be noted that in case the bit-map vector is dropped from one CSI partition feedback, the UE should calculate the LC matrix in that partition given the information that b_t is

dropped in that partition. In other words, is calculated assuming a pre-defmed value for the bit-map from a previous transmission of that particular partition t.

[0052] Similarly, in some implementations, within a CSI Report partition, the bit-map vector b_t has a higher priority than FD basis subset of that particular CSI report partition

Wf,t. [0053] Example implementation 2 - In some implementations, for example, at time instant x, the UE may feed back a bit sequence g in UCI part 1, where depending on the value of g, the UE may decide to update a partition k, a next partition k+1, transmit nothing, or simply reset the schedule and start with the first partition again. The final updated partition is sent in UCI part 2.

Table 1- example embodiment on how the bit sequence g can be interpreted

[0054] The above example implementation provides flexibility at the UE as it has an explicit knowledge of the channel and it can choose to prioritize specific partitions based on their strength or autocorrelation over time. In a baseline configuration, the UE may make one full update which may include and b. The gNB may use this information

to construct precoding vector and use it for DL precoding, etc.

[0055] Example implementation 3 - In some implementations, for example, the incremental CSI/PMI feedback may be realized upon static configuration of N CSI reports by gNB. In particular, schemes A and scheme B illustrated in FIG. 4 may be obtained by configuring X and X+l CSI reports, via appropriate RRC signaling, respectively. In other words, each of the CSI reports may be configured to report CSI/PMI related to a subset of FD beams whose size is £ M.

[0056] Example implementation 4 - In some implementations, for example, it may be possible to generalize example implementations 1.1 and 1.2 described above such that the partition may be taken considering the two dimensions: space and frequency. As shown in FIG. 6A, a partition may be taken as a subset of beams and FD components. And at each time instant, a different partition is fed back. For example, the partition at t=0, could be including the strongest beam (on row) and the left most columns (strongest FD components) to make sure it is the strongest partition. In addition, one or more partitions can be non contiguous as shown in FIG. 6B. For example, at t=0, the 2D partition includes the strongest beams on both polarizations (which are on different rows). In the following we assume the index of a 2D partition is the time instant at which it is transmitted, e.g., t in FIG. 6B.

[0057] Example implementation 5 - In some implementations, for example, the example implementation 1 to 4 are constructed assuming NR type II CSI feedback scheme. The same implementations may also be applied assuming an explicit CSI scheme. For example, for time domain explicit CSI feedback, the spatially aggregated channel frequency response (CFR) is compressed in delay domain via projection matrix is

the number of receive antennas, N_a is the number of active subcarriers and N_s is the length of the common channel support i.e. location of active taps among all transmit-receive beams.

[0058] In some implementations, for example, may be spatially aggregated

using GoB matrix W₁ which is applied on the actual CFR is obtained

at UE side after UE performs channel estimation using DL reference signal CSI-RS.

[0059] The columns of ^are drawn from DFT basis at the locations of the

common channel support. can be regarded as the counterpart of the FD basis subset

matrix W_f in Rel.16, whereas is the counterpart of

[0060] In case the strength of the time domain taps (columns) inside is known

at both sides of UE and gNB then a fixed schedule is devised and the UE would send the quantized taps in their order of strength according to schemes A and B. UE may inform gNB about its decision on next partitioned CSI feedback, with the four options in Table 1 as an example. Example of a case where the strength order of the taps is known at both sides will be if a compressive sensing scheme is used at UE side (e.g. OMP), it will discover the channel taps in descending order of power or alternatively the power order of the taps is simply fed back to the gNB side by the UE.

[0061] Additional example implementations are described herein.

[0062] Example 1. A method of communications, comprising: performing, by a user equipment (UE), channel estimation of a downlink reference signal received from a network node, the channel estimation represented by a compressed linear combination coefficient (LCC) matrix, a set of spatial domain beams, and a set of frequency domain basis vectors; generating, by the user equipment (UE), a plurality of partitions, a partition of the plurality of partitions being generated based on a combination of one or more of: linear combination coefficients (LCCs) of the compressed linear combination coefficient (LCC) matrix, a bitmap which indicates whether a corresponding linear combination coefficient (LCC) is a non-zero or zero linear combination coefficient (LCC), and a frequency domain (FD) component matrix; and transmitting, by the user equipment (UE), a first partition of the generated plurality of partitions to the network node.

[0063] Example 2. The method of Example 1, further comprising: transmitting, by the user equipment (UE), a second partition of the generated plurality of partitions to the network node.

[0064] Example 3. The method of any of Examples 1-2, wherein sizes of the first partition and/or the second partition are selected based on sizes of scheduled physical uplink shared channel (PUSCH) or physical uplink control channel (PUCCH) resources.

[0065] Example 4. The method of any of Examples 1-3, further comprising: transmitting updates for the first partition at a first time interval and/or the second partition at a second time interval, wherein the first time interval is same or different from the second time interval.

[0066] Example 5. The method of any of Examples 1-4, wherein the first interval and/or second time interval are configured with different values for different layers.

[0067] Example 6. The method of any of Examples 1-5, further comprising: receiving channel state information (CSI) reports configuration information from the network node, the configuration information indicating frequency domain (FD) beams to be included in a particular channel state information (CSI) report; generating channel state information (CSI) reports based on the received configuration information; and transmitting the generated channel state information (CSI) reports to the network node.

[0068] Example 7. The method of any of Examples 1-6, wherein the partitions are channel state information (CSI) report partitions, and wherein the configuration information indicates one or more of: a number of the partitions, sizes of the partitions, and priorities for partitions.

[0069] Example 8. The method of any of Examples 1-7, wherein the plurality of partitions is generated based on partitioning of the channel estimation jointly using incremental reporting of space and frequency components.

[0070] Example 9. The method of any of Examples 1-8, wherein the plurality of partitions includes non-contiguous partitions.

[0071] Example 10. The method of any of Examples 1-9, wherein a frequency domain (FD) component is a vector that is selected from a frequency domain basis, and each column of the linear combination coefficient (LCC) matrix being associated to a frequency domain (FD) component. [0072] Example 11. The method any of Examples 1-10, wherein the frequency domain (FD) component with a lower index value has higher priority.

[0073] Example 12. The method of any of Examples 1-11, wherein the plurality of partitions is prioritized according to indices of the corresponding FD components.

[0074] Example 13. The method of any of Examples 1-12, wherein the downlink reference signal is a channel state information-reference signal (CSI-RS).

[0075] Example 14. The method of any of Examples 1-13, further comprising: determining that the component that is associated with the strongest linear coefficient is not at position zero; and sending an indicator to the network node identifying the component that is associated with the strongest linear combination coefficient.

[0076] Example 15. The method of any of Examples 1-14, wherein the network node is a radio access network node.

[0077] Example 16. An apparatus comprising means for performing the method of any of Examples 1-15.

[0078] Example 17. A non-transitory computer-readable storage medium having stored thereon computer executable program code which, when executed on a computer system, causes the computer system to perform the steps of any of Examples 1-15.

[0079] Example 18. An apparatus, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: perform, by a user equipment (UE), channel estimation of a downlink reference signal received from a network node, the channel estimation represented by a compressed linear combination coefficient (LCC) matrix, a set of spatial domain beams, and a set of frequency domain basis vectors; generate, by the user equipment (UE), a plurality of partitions, a partition of the plurality of partitions being generated based on a combination of one or more of: linear combination coefficients (LCCs) of the compressed linear combination coefficient (LCC) matrix, a bitmap which indicates whether a corresponding linear combination coefficient (LCC) is a non-zero or zero linear combination coefficient (LCC), and a frequency domain (FD) component matrix; and transmit, by the user equipment (UE), a first partition of the generated plurality of partitions to the network node.

[0080] Example 19. The apparatus of Example 18, further cause the apparats to: transmit, by the user equipment (UE), a second partition of the generated plurality of partitions to the network node.

[0081] Example 20. The apparatus of any of Examples 18-19, wherein sizes of the first partition and/or the second partition are selected based on sizes of scheduled physical uplink shared channel (PUSCH) or physical uplink control channel (PUCCH) resources.

[0082] Example 21. The apparatus of any of Examples 18-20, further cause the apparats to: transmit updates for the first partition at a first time interval and/or the second partition at a second time interval, wherein the first time interval is same or different from the second time interval.

[0083] Example 22. The apparatus of any of Examples 18-21, wherein the first interval and/or second time interval are configured with different values for different layers.

[0084] Example 23. The apparatus of any of claims 18-22, further cause the apparats to: receive channel state information (CSI) reports configuration information from the network node, the configuration information indicating frequency domain (FD) beams to be included in a particular channel state information (CSI) report; generate channel state information (CSI) reports based on the received configuration information; and transmit the generated channel state information (CSI) reports to the network node.

[0085] Example 24. The apparatus of any of Examples 18-23, wherein the partitions are channel state information (CSI) report partitions, and wherein the configuration information indicates one or more of: a number of the partitions, sizes of the partitions, and priorities for partitions.

[0086] Example 25. The apparatus of any of Examples 18-24, wherein the plurality of partitions is generated based on partitioning of the channel estimation jointly using incremental reporting of space and frequency components.

[0087] Example 26. The apparatus of any of Examples 18-25, wherein the plurality of partitions includes non-contiguous partitions.

[0088] Example 27. The apparatus of any of Examples 18-26, wherein a frequency domain (FD) component is a vector that is selected from a frequency domain basis, and each column of the linear combination coefficient (LCC) matrix being associated to a frequency domain (FD) component.

[0089] Example 28. The apparatus any of Examples 18-27, wherein the frequency domain (FD) component with a lower index value has higher priority.

[0090] Example 29. The apparatus of any of Examples 18-28, wherein the plurality of partitions is prioritized according to indices of the corresponding FD components.

[0091] Example 30. The apparatus of any of Examples 18-29, wherein the downlink reference signal is a channel state information-reference signal (CSI-RS).

[0092] Example 31. The apparatus of any of Examples 18-30, further cause the apparats to: determine that the component that is associated with the strongest linear coefficient is not at position zero; and send an indicator to the network node identifying the component that is associated with the strongest linear combination coefficient.

[0093] Example 32. The apparatus of any of Examples 18-31 , wherein the network node is a radio access network node.

[0094] FIG. 3 illustrates an example of PMI partitioning along LCC matrix columns

300, according to at least one example implementation.

[0095] In some implementations, for example, a

grid-of-beam (GoB) matrix may be shown as below where N and N₂ are the number of antenna ports in azimuth and elevation direction and L is the number of beams per polarization

[0096] In an example implementation for a layer l and subband k, the 2L x 1 linear combination (LC) coefficients of the long-term spatial beams may be denoted by:

[0097] In another example implementation, for a layer l, the LC coefficients in

may be built from N₃ subband eigenvectors assuming N _sb subbands as:

[0098] For Rel. 16 the linear combining coefficients L for layer l , of size

2 L x M, where M < N₃ is the number of FD coefficients and may be written as:

[0099] maY be built at UE given knowledge of and as shown

below:

[00100] In the baseline scheme, at every CSI feedback instant, in UCI part 2, the UE would feedback quantized matrices

and In addition, a bitmap b of size

2L x M is also fed back to gNB to indicate which coefficients inside the sparse matrix a^re non-zero. In UCI part 1, the number of non-zero coefficients (NNZC) inside

IS fed back by UE so that the gNB can estimate the payload in UCI part 2.

[00101] The highest overhead in the process comes from feeding back quantized coefficients and bit-map b.

[00102] Unlike the baseline case, we propose to break the data inside and

possibly into several partitions. Each partition contains a group of column(s) inside and possibly Partitions are selected out of the columns according to their

order inside the matrices : and possibly That means for example,

partition 1 comes from columns 1 to M' and partition 2 contains columns M' + 1 to columns

[00103] Because of the index re-mapping, the weight or the contribution of the columns inside decreases as the column index increases, i.e. first columns are more important

than subsequent columns. That is why the partitions can be sent according to their order of significance.

[00104] FIG. 4 illustrates feedback schemes 400, for example, schemes A and B, according to at least one example implementation. In FIG. 4, it should be noted that the parts in bold refer to “new” parts (or portions) fed back at that time instant.

[00105] In an example implementation, in Scheme A (410), at each time instant from t=0 to t=X-l, a portion of the

(e.g., a partition) and corresponding bit-map (possibly also corresponding part of ) may be fed back from the UE to the gNB, with the effect that the

matrix at the gNB keeps growing. In addition, the schedule may imply that some partitions may be updated at a higher rate than others, in that case with such a repetitive update that the matrix may be of the same size as it was before the repetitive update. This

particular scheme may enable to spread the CSI payload over time which reduces CSI dropping, especially in high connection density or multi-TRP scenarios.

[00106] In another example implementation, in Scheme B (420), a full update may be made in the past at time at t = -Y. Then, starting at time t=0 and up to the next full update, different parts inside the may be updated. This particular scheme may be used, for

example, whenever sufficient CSI reporting resources are available and/or to reduce CSI aging impact.

[00107] FIG. 5A illustrates an example implementation of Scheme A 500, according to at least one example implementation. FIG. 5B illustrates an example implementation of Scheme B 560, according to at least one more example implementation. In FIGs. 5A and 5B, UE-gNB procedure using proposed scheme variants A and B are illustrated.

[00108] In some implementations, for example, indicates partition #x fed back at

time t by UE, whereas indicates partition #x stored inside from an old feedback and

is the full matrix available at gNB. The same notation may be used with the bit-map b and FD basis subset matrix

[00109] As illustrated in FIG. 5A, with every short-term feedback instant, which can be triggered, trigger a CSI-RS transmission, or neither, UE may make a decision whether or not partition #t should be fed back or feedback partition #t+x or to feedback partition#0 or feedback nothing. The decision may be conveyed to gNB via bit-sequence g in UCI part 1. Depending on g , gNB can estimate upcoming payload in UCI part 2 and may interpret the data sent in UCI part 1.

[00110] In some implementations, FIG. 5B illustrates UE-gNB procedure with scheme B. It should be noted that, the main difference from scheme A, for example, may be that a full update is made once at the beginning before the incremental updates. This may change the way g is interpreted at gNB side, for example, if UE does not send an update for a particular partition x at time t

its value inside

is taken from the old value of that partition inside

. The same process applies for bit-map b and FD basis subset matrix

as well

[00111] FIG. 6A illustrates an example of joint space and frequency incremental reporting mechanism 600, according to at least one example implementation. FIG. 6B illustrates an additional example with non-contiguous partitions 660, according to at least one more example implementation.

[00112] In some implementations, a partition may be generated by considering two dimensions: space and frequency. As shown in FIG. 6A, a partition may be defined (or considered) as a subset of beams and FD components, wherein at each time instant, a

different partition is fed back to the network node. For example, a partition at t=0 may include the strongest beam (on row) and the left most columns (strongest FD components) to ensure it is the strongest partition.

[00113] In addition, in some implementations, for example, one or more partitions may be non-contiguous as shown in Figure 6B. For example, at t=0, the 2D partition may include the strongest beams on both polarizations (e.g., which may be on different rows). In some implementations, it can be assumed that the index of a 2D partition is the time instant at which it is transmitted, e.g., t in FIG. 6B. At t=l, the 2^nd partition may be generated using the left most FD components as in FIG. 6A, or at the same strongest beam position and higher FD index, or both as shown in FIG. 6B.

[00114] In some implementations, for example, in case the ordering of the strength of the SD beams that are known apriori to the gNB (e.g., via a UE feedback indicating relative order of the SD beams with respect to each other), the partitions which fall on the location of stronger SD beams and stronger FD components may be given a higher priority in the schedule, e.g., updated more frequently. In Rel. 15 and 16, at least the location of the strongest SD beam is fed back to the gNB. In one example implementation, for instance, in Rel.16 (or later), 2D partitions with lower index have higher priority than 2D partitions of higher index in a UCI omission rule, for example, in a CSI Report, 2D partitions with lower indices may have higher priority than 2D partitions with higher indices. [00115] FIG. 7 is a block diagram 700 of a wireless station (e.g., an user equipment (UE)/user device or AP/gNB/eNB/MgNB/SgNB/NG-RAN node) according to an example implementation. The wireless station 700 may include, for example, one or more RF (radio frequency) or wireless transceivers 702A, 702B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit/entity (controller) 704/708 to execute instructions or software and control transmission and receptions of signals, and a memory 706 to store data and/or instructions.

[00116] Processor 704 may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor 704, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver 702 (702 A or 702B). Processor 704 may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver 702, for example). Processor 704 may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor 704 may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor 704 and transceiver 702 together may be considered as a wireless transmitter/receiver system, for example.

[00117] In addition, referring to FIG. 7, a controller (or processor) 708 may execute software and instructions, and may provide overall control for the station 700, and may provide control for other systems not shown in FIG. 7, such as controlling input/output devices (e.g., display, keypad), and/or may execute software for one or more applications that may be provided on wireless station 700, such as, for example, an email program, audio/video applications, a word processor, a Voice over IP application, or other application or software. Moreover, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor 704, or other controller or processor, performing one or more of the functions or tasks described above.

[00118] According to another example implementation, RF or wireless transceiver(s) 702A/702B may receive signals or data and/or transmit or send signals or data. Processor 704 (and possibly transceivers 702A/702B) may control the RF or wireless transceiver 702 A or 702B to receive, send, broadcast or transmit signals or data. [00119] The aspects are not, however, restricted to the system that is given as an example, but a person skilled in the art may apply the solution to other communication systems.

Another example of a suitable communications system is the 5G concept. It is assumed that network architecture in 5G will be quite similar to that of the LTE-advanced. 5G is likely to use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

[00120] It should be appreciated that future networks will most probably utilize network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labor between core network operations and base station operations may differ from that of the LTE or even be non-existent.

[00121] Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Implementations may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Implementations may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Implementations of the various techniques may also include implementations provided via transitory signals or media, and/or programs and/or software implementations that are downloadable via the Internet or other network(s), either wired networks and/or wireless networks. In addition, implementations may be provided via machine type communications (MTC), and also via an Internet of Things (IOT).

[00122] The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers.

[00123] Furthermore, implementations of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers,...) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals. The rise in popularity of smartphones has increased interest in the area of mobile cyber-physical systems. Therefore, various implementations of techniques described herein may be provided via one or more of these technologies.

[00124] A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit or part of it suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[00125] Method steps may be performed by one or more programmable processors executing a computer program or computer program portions to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[00126] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer, chip or chipset. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

Claims

WHAT IS CLAIMED IS:

1. A method of communications, comprising: performing, by a user equipment (UE), channel estimation of a downlink reference signal received from a network node, the channel estimation represented by a compressed linear combination coefficient (LCC) matrix, a set of spatial domain beams, and a set of frequency domain basis vectors; generating, by the user equipment (UE), a plurality of partitions, a partition of the plurality of partitions being generated based on a combination of one or more of: linear combination coefficients (LCCs) of the compressed linear combination coefficient (LCC) matrix, a bitmap which indicates whether a corresponding linear combination coefficient (LCC) is a non-zero or zero linear combination coefficient (LCC), and a frequency domain (ED) component matrix; and transmitting, by the user equipment (UE), a first partition of the generated plurality of partitions to the network node.

2. The method of claim 1, further comprising: transmitting, by the user equipment (UE), a second partition of the generated plurality of partitions to the network node.

3. The method of any of claims 1-2, wherein sizes of the first partition and/or the second partition are selected based on sizes of scheduled physical uplink shared channel (PUSCH) or physical uplink control channel (PUCCH) resources.

4. The method of any of claims 1-3, further comprising: transmitting updates for the first partition at a first time interval and/or the second partition at a second time interval, wherein the first time interval is same or different from the second time interval.

5. The method of any of claims 1-4, wherein the first interval and/or second time interval are configured with different values for different layers.

6. The method of any of claims 1-5, further comprising: receiving channel state information (CSI) reports configuration information from the network node, the configuration information indicating frequency domain (FD) beams to be included in a particular channel state information (CSI) report; generating channel state information (CSI) reports based on the received configuration information; and transmitting the generated channel state information (CSI) reports to the network node.

7. The method of any of claims 1-6, wherein the partitions are channel state information (CSI) report partitions, and wherein the configuration information indicates one or more of: a number of the partitions, sizes of the partitions, and priorities for partitions.

8. The method of any of claims 1-7, wherein the plurality of partitions is generated based on partitioning of the channel estimation jointly using incremental reporting of space and frequency components.

9. The method of any of claims 1-8, wherein the plurality of partitions includes non contiguous partitions.

10. The method of any of claims 1-9, wherein a frequency domain (FD) component is a vector that is selected from a frequency domain basis, and each column of the linear combination coefficient (LCC) matrix being associated to a frequency domain (FD) component.

11. The method any of claims 1-10, wherein the frequency domain (FD) component with a lower index value has higher priority.

12. The method of any of claims 1-11, wherein the plurality of partitions is prioritized according to indices of the corresponding FD components.

13. The method of any of claims 1-12, wherein the downlink reference signal is a channel state information-reference signal (CSI-RS).

14. The method of any of claims 1-13, further comprising: determining that the component that is associated with the strongest linear coefficient is not at position zero; and sending an indicator to the network node identifying the component that is associated with the strongest linear combination coefficient.

15. The method of any of claims 1-14, wherein the network node is a radio access network node.

16. An apparatus comprising means for performing the method of any of claims 1-15.

17. A non-transitory computer-readable storage medium having stored thereon computer executable program code which, when executed on a computer system, causes the computer system to perform the steps of any of claims 1-15.

18. An apparatus, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: perform, by a user equipment (UE), channel estimation of a downlink reference signal received from a network node, the channel estimation represented by a compressed linear combination coefficient (LCC) matrix, a set of spatial domain beams, and a set of frequency domain basis vectors; generate, by the user equipment (UE), a plurality of partitions, a partition of the plurality of partitions being generated based on a combination of one or more of: linear combination coefficients (LCCs) of the compressed linear combination coefficient (LCC) matrix, a bitmap which indicates whether a corresponding linear combination coefficient (LCC) is a non-zero or zero linear combination coefficient (LCC), and a frequency domain (ED) component matrix; and transmit, by the user equipment (UE), a first partition of the generated plurality of partitions to the network node.

19. The apparatus of claim 18, further cause the apparats to: transmit, by the user equipment (UE), a second partition of the generated plurality of partitions to the network node.

20. The apparatus of any of claims 18-19, wherein sizes of the first partition and/or the second partition are selected based on sizes of scheduled physical uplink shared channel (PUSCH) or physical uplink control channel (PUCCH) resources.

21. The apparatus of any of claims 18-20, further cause the apparats to: transmit updates for the first partition at a first time interval and/or the second partition at a second time interval, wherein the first time interval is same or different from the second time interval.

22. The apparatus of any of claims 18-21, wherein the first interval and/or second time interval are configured with different values for different layers.

23. The apparatus of any of claims 18-22, further cause the apparats to: receive channel state information (CSI) reports configuration information from the network node, the configuration information indicating frequency domain (FD) beams to be included in a particular channel state information (CSI) report; generate channel state information (CSI) reports based on the received configuration information; and transmit the generated channel state information (CSI) reports to the network node.

24. The apparatus of any of claims 18-23, wherein the partitions are channel state information (CSI) report partitions, and wherein the configuration information indicates one or more of: a number of the partitions, sizes of the partitions, and priorities for partitions.

25. The apparatus of any of claims 18-24, wherein the plurality of partitions is generated based on partitioning of the channel estimation jointly using incremental reporting of space and frequency components.

26. The apparatus of any of claims 18-25, wherein the plurality of partitions includes non contiguous partitions.

27. The apparatus of any of claims 18-26, wherein a frequency domain (FD) component is a vector that is selected from a frequency domain basis, and each column of the linear combination coefficient (LCC) matrix being associated to a frequency domain (FD) component.

28. The apparatus any of claims 18-27, wherein the frequency domain (FD) component with a lower index value has higher priority.

29. The apparatus of any of claims 18-28, wherein the plurality of partitions is prioritized according to indices of the corresponding FD components.

30. The apparatus of any of claims 18-29, wherein the downlink reference signal is a channel state information-reference signal (CSI-RS).

31. The apparatus of any of claims 18-30, further cause the apparats to: determine that the component that is associated with the strongest linear coefficient is not at position zero; and send an indicator to the network node identifying the component that is associated with the strongest linear combination coefficient.

32. The apparatus of any of claims 18-31 , wherein the network node is a radio access network node.