SYSTEMS AND METHODS FOR CHANNEL STATE INFORMATION REPORTING FOR CHANNEL PREDICTION

TECHNICAL FIELD

The present disclosure relates, in general, to wireless communications and, more particularly, systems and methods for Channel State Information (CSI) reporting for channel prediction.

BACKGROUND

Multi-antenna techniques can significantly increase the data rates and reliability of a wireless communication system. The performance is in particular improved if both the transmitter and the receiver are equipped with multiple antennas, which results in a multiple- input multiple-output (MIMO) communication channel. Such systems and/or related techniques are commonly referred to as MIMO.

The New Radio (NR) standard is currently evolving with enhanced MIMO support. A core component in NR is the support of MIMO antenna deployments and MIMO related techniques like for instance spatial multiplexing. The spatial multiplexing mode is aimed for high data rates in favorable channel conditions. FIGURE 1 illustrates a spatial multiplexing operation. More specifically, FIGURE 1 illustrates a transmission structure of precoded spatial multiplexing mode in NR.

As seen in FIGURE 1, the information carrying symbol vector 5 is multiplied by an NT x r precoder matrix W, which serves to distribute the transmit energy in a subspace of the NT (corresponding to NT antenna ports) dimensional vector space. The precoder matrix is typically selected from a codebook of possible precoder matrices, and typically indicated by means of a precoder matrix indicator (PMI), which specifies a unique precoder matrix in the codebook for a given number of symbol streams. The r symbols in s each correspond to a layer and r is referred to as the transmission rank. In this way, spatial multiplexing is achieved since multiple symbols can be transmitted simultaneously over the same time/frequency resource element (TFRE). The number of symbols r is typically adapted to suit the current channel properties. NR uses Orthogonal Frequency Domain Multiplexing (OFDM) in the downlink (and optionally allows Direct Fourier Transform (DFT) precoded OFDM in the uplink for rank- 1 transmission). Thus, the receive for a certain TFRE on subcarrier n (or alternatively data TFRE number ri) is thus modeled by where e _n is a noise/interference vector obtained as realizations of a random process. The precoder W can be a wideband precoder, which is constant over frequency, or frequency selective.

The precoder matrix W is often chosen to match the characteristics of the MIMO channel matrix H _n , resulting in so-called channel dependent precoding. This is also commonly referred to as closed-loop precoding and essentially strives for focusing the transmit energy into a subspace which is strong in the sense of conveying much of the transmitted energy to the User Equipment (UE).

In closed-loop precoding for the NR downlink, the UE transmits, based on channel measurements in the downlink, recommendations to the gNodeB (gNB) of a suitable precoder to use. The gNB configures the UE to provide feedback according to CSI-ReportConfig and may transmit C Si-Reference Signals (CSI-RS) and configure the UE to use measurements of CSI-RS to feedback recommended precoding matrices that the UE selects from a codebook. A single precoder that is supposed to cover a large bandwidth (wideband precoding) may be fed back. It may also be beneficial to match the frequency variations of the channel and instead feed back a frequency-selective precoding report, e.g. several precoders, one per subband. This is an example of the more general case of CSI feedback, which also encompasses feeding back other information than recommended precoders to assist the gNB in subsequent transmissions to the UE. Such other information may include channel quality indicators (CQIs) as well as transmission rank indicator (RI). In NR, CSI feedback can be either wideband, where one CSI is reported for the entire channel bandwidth, or frequency-selective, where one CSI is reported for each subband, which is defined as a number of contiguous resource blocks ranging between 4-32 Physical Resource Blocks (PRBs) depending on the band width part (BWP) size.

Given the CSI feedback from the UE, the gNB determines the transmission parameters it wishes to use to transmit to the UE, including the precoding matrix, transmission rank, and modulation and coding scheme (MCS). These transmission parameters may differ from the recommendations the UE makes. The transmission rank, and thus the number of spatially multiplexed layers, is reflected in the number of columns of the precoder W. For efficient performance, it is important that a transmission rank that matches the channel properties is selected.

Two-dimensional (2D) antenna arrays may be at least partly described by the number of antenna columns corresponding to the horizontal dimension N _h , the number of antenna rows corresponding to the vertical dimension N _v and the number of dimensions corresponding to different polarizations N _p . The total number of antennas is thus N = N _h N _v N _p . The concept of an antenna is non-limiting in the sense that it can refer to any virtualization (e.g., linear mapping) of the physical antenna elements. For example, pairs of physical sub-elements could be fed the same signal, and hence share the same virtualized antenna port.

FIGURE 2 illustrates an example of a 4x4 array with dual-polarized antenna elements. Specifically, FIGURE 2 is an illustration of a two-dimensional antenna array of dual-polarized antenna elements (N _P = 2) , with N _h = 4 horizontal antenna elements and N _v = 4 vertical antenna elements.

Precoding may be interpreted as multiplying the signal with different beamforming weights for each antenna prior to transmission. A typical approach is to tailor the precoder to the antenna form factor, i.e. taking into account N _h , N _v and N _p when designing the precoder codebook.

Channel State Information Reference Signals (CSI-RS)

For CSI measurement and feedback, CSI-RS are defined. A CSI-RS is transmitted on each antenna port and is used by a UE to measure the downlink channel between each of the transmit antenna ports and each of its receive antenna ports. The transmit antenna ports are also referred to as CSI-RS ports. The supported number of antenna ports in NR are { 1,2,4,8,12,16,24,32}. By measuring the received CSI-RS, a UE can estimate the channel that the CSI-RS is traversing, including the radio propagation channel and antenna gains. The CSI- RS for the above purpose is also referred to as Non-Zero Power (NZP) CSI-RS.

CSI-RS can be configured to be transmitted in certain Resource Elements (REs) in a slot and certain slots. FIGURE 3 illustrates an example of CSI-RS REs for 12 antenna ports, where IRE per RB per port is shown.

In addition, interference measurement resource (IMR) is also defined in NR for a UE to measure interference. An IMR resource contains 4 REs, either 4 adjacent RE in frequency in the same OFDM symbol or 2 by 2 adjacent REs in both time and frequency in a slot. By measuring both the channel based on NZP CSI-RS and the interference based on an IMR, a UE can estimate the effective channel and noise plus interference to determine the CSI, i.e. rank, precoding matrix, and the channel quality.

Furthermore, a UE in NR may be configured to measure interference based on one or multiple NZP CSI-RS resource.

CSI framework in NR

In NR, a UE can be configured with multiple CSI reporting settings and multiple CSI- RS resource settings. Each resource setting can contain multiple resource sets, and each resource set can contain up to 8 CSI-RS resources. For each CSI reporting setting, a UE feeds back a CSI report.

Each CSI reporting setting contains at least the following information:

• a CSI-RS resource set for channel measurement;

• an IMR resource set for interference measurement;

• optionally, a CSI-RS resource set for interference measurement;

• time-domain behavior, i.e. periodic, semi-persistent, or aperiodic reporting;

• frequency granularity, i.e. wideband or subband;

• CSI parameters to be reported such as Rank Indicator (RI), Precoder Matrix Indicator (PMI), CQI, and CSI-RS resource indicator (CRI) in case of multiple CSI-RS resources in a resource set;

• codebook types, i.e. type I or II, and codebook subset restriction;

• measurement restriction; and

• subband size (One out of two possible subband sizes is indicated, the value range depends on the bandwidth of the BWP. One CQI/PMI (if configured for subband reporting) is fed back per subband).

When the CSI-RS resource set in a CSI reporting setting contains multiple CSI-RS resources, one of the CSI-RS resources is selected by a UE and a CRI is also reported by the UE to indicate to the gNB about the selected CSI-RS resource in the resource set, together with RI, PMI and CQI associated with the selected CSI-RS resource.

For aperiodic CSI reporting in NR, more than one CSI reporting settings, each with a different CSI-RS resource set for channel measurement and/or resource set for interference measurement can be configured and triggered at the same time. In this case, multiple CSI reports are aggregated and sent from the UE to the gNB in a single PUSCH. NR rel-15 Type II codebook

For the NR Type II codebook in Rel-15, the precoding vector for each layer and subband is expressed in 3GPP specification 3GPP TR 38.214 as:

If we restructure the above formula and express it a bit simpler, we can form the precoder vector for a certain layer I = 0,1, polarization p = 0,1 and resource block

S is the subband size and N _SB is the number of subbands in the CSI reporting bandwidth. Hence, the change in a beam coefficient across frequency is determined based on the 2N _SB parameters ). Where the subband amplitude parameter is quantized using 0-1 bit and the subband phase parameter is quantized using 2-3 bits, depending on codebook configuration.

NR Re I- 16 enhanced Type II port selection codebook

The enhanced Type II (eType II) port selection (PS) codebook was introduced in Rel- 16, which is intended to be used for beamformed CSI-RS, where each CSI-RS port covers a small portion of the cell coverage area with high beamforming gain (comparing to non- beamformed CSI-RS). Although it is up to the gNB implementation, it is usually assumed that each CSI-RS port is transmitted in a 2D spatial beam which has a main lobe with an azimuth pointing angle and an elevation pointing angle. The actual precoder matrix used for CSI-RS is transparent to the UE. Based on the measurement, the UE selects the best CSI-RS ports and recommends a rank, a precoding matrix, and a CQI conditioned on the rank and the precoding matrix to the gNB to use for downlink (DL) transmission. The precoding matrix comprises linear combinations of the selected CSI-RS ports. The eType II PS codebook can be used by the UE to feedback the selected CSI-RS ports and the combining coefficients. Structure, configuration and reporting of eType II PS codebook

For a given transmission layer Z, with I G {1, v} and v being the rank indicated by the rank indicator (RI), the precoder matrix is given by a size where

• S is the number of CSI-RS ports.

• is the number of subbands for PMI, where o The value R = {1,2} (the PMI subband size indicator) is RRC configured. o N _SB is the number of CQI subbands, which is also RRC configured.

• The maximum RI value v is set according to the configured higher layer parameter typeII-RI-Restriction-rl6. The UE shall not report v > 4.

For each layer I, the precoding matrix (see FIGURE 4) and is normalized such that

FIGURE 4 illustrates factorization of the Rel-16 Type II port-selection precoder for layer /, where:

Port selection matrix W ₃ : port selection precoder matrix that can be factorized into denotes Kronecker product and port selection matrix, w contains one element 1 that indicates the selected CSI-RS port while all the other elements are 0s. L is the number of selected CSI-RS ports from each polarization and the same ports are selected for both polarizations.

• Supported L values can be found in Table 1.

• Selected CSI-RS ports are indicated by which is reported by the UE to gNB. o The value of is determined by UE based on CSI-RS measurement. o The value of d is configured with the higher layer parameter portSelectionSamplingSize, where d E {1, 2, 3, 4} and d <

• is common for all layers.

Frequency-domain (FD) compression matrix compression matrix for layer Z, where is the number of selected FD basis vectors, which depends on the rank indicator v and the RRC configured parameter p _v . Supported values of p _v can be found in Table 1. basis vectors that are selected from N ₃ orthogonal DFT basis vectors denotes transpose. o F a one-step free selection is used.

For each layer, FD basis selection is indicated with a bit combinatorial indicator. In TS 38.214, the combinatorial indicator is given by the index i _{16 l} where I corresponds to the layer index. This combinatorial index is reported by UE to the gNB per layer. o For a two-step selection with layer-common intermediary subset

(IntS) is used. In this first step, a window-based layer-common IntS selection is used, which is parameterized by The IntS consists of FD basis vectors and In TS 38.214, the selected IntS is reported by the UE to the gNB via the parameter , which is reported per layer as part of the PMI reported. The second step subset selection is indicated by an

-bit combinatorial indicator for each layer. In TS

38.214, the combinatorial indicator is given by the index where I corresponds to the layer index. This combinatorial index is reported by UE to the gNB per layer. o is layer-specific.

Linear combination coefficient matrix

• ₂ ,i _v matrix that contains coefficients for linearly combining the selected M _v FD basis vectors and the selected 2L CSLRS ports.

• For layer Z, only a subset of coefficients are non-zero and reported. The remaining non-reported coefficients are considered zero. is the maximum number of non-zero coefficients per layer, where β is a RRC configured parameter. Supported β values are shown in Table 1. o For v ∈ {2, 3, 4}, the total number of non-zero coefficients summed across all layers, K shall satisfy o Selected coefficient subset for each layer is indicated with in a size 2LM _V bitmap, i _{1 7} i . o The selected CSLRS port associated with the strongest coefficient of layer I is identified by

• The amplitude coefficients in are indicated by and and the phase coefficients in are indicated by .

• layer-specific.

Table 1 Rel-16 Type II PS codebook parameter configurations for L, p _v and β

The PMI reported by the UE comprises codebook indices and i ₂ where

The precoding matrix is the PMI values according to Table 2.

Table 2: Precoding matrix indicated by PMI. For Rel-16 Enhanced Type II CSI feedback, a CSI report comprises of two parts. Part 1 has a fixed payload size and is used to identify the number of information bits in Part 2. Part 1 contains RI, CQI, and an indication of the overall number of non-zero amplitude coefficients across layers, i.e., Part 2 contains the PMI. Part 1 and 2 are separately encoded.

Frequency Division Duplex (FDD)-based reciprocity operation and Rel-17 Type II port selection codebook

In FDD operation, the uplink (UL) and DL transmissions are carried out on different frequencies, thus the propagation channels in UL and DL are not reciprocal as in the Time Division Duplex (TDD) case. Despite this, some physical channel parameters such as, for example, delays and angles to different clusters, which depend on the spatial properties of the channel but not the carrier frequency, are reciprocal between UL and DL. Such properties can be exploited to obtain partial reciprocity based FDD transmission. The reciprocal part of the channel can be combined with the non-reciprocal part in order to obtain the complete channel. An estimate of the non-reciprocal part can be obtained by feedback from the UE. In 3 GPP RANI, it has been agreed that in Rel-17, the Rel-16 Type II port selection codebook will be enhanced to support the above the above-mentioned FDD-based reciprocity operation. It has been agreed in 3GPP RANl#104e that the Rel-17 Type II port selection codebook will adopt the same codebook structure as the Rel-16 Type II port selection codebook, i.e., the codebook consists VFi, VF ₂ , and W?. Discussion regarding the details of the codebook component, such as dimension of each matrix, is still ongoing.

Procedure for FDD-based reciprocity operation

FIGURES 5A-5D illustrate an example procedure for reciprocity based FDD transmission scheme that includes four steps and assumes that NR Rel.16 enhanced Type II port-selection codebook is used.

In Step 1 illustrated I FIGURE 5A, the UE is configured with SRS by the gNB and the UE transmits SRS in the UL for the gNB to estimate the angles and delays of different clusters, which are associated with different propagation paths.

In Step 2 illustrated in FIGURE 5B, in gNB implementation algorithm, the gNB selects dominant clusters according to the estimated angle-delay power spectrum profile, based on which a set of spatial-domain and frequency-domain (SD-FD) basis pairs are computed by gNB for CSI-RS beamforming. Each SD-FD pair corresponds to a CSI-RS port with certain delay being pre-compensated. Each CSI-RS port resource can contain one or multiple SD-FD basis pairs by applying different delays on different resource elements of the resource. gNB precodes all the CSI-RS ports in a configured CSI-RS resource or multiple CSI-RS resources to the UE, with each configured CSI-RS resource containing the same number of SD-FD basis pairs.

In Step 3 illustrated in FIGURE 5C, gNB has configured the UE to measure CSI-RS, and the UE measures the received CSI-RS ports and then determines a type II CSI including RI, PMI for each layer and CQI. The precoding matrix indicated by the PMI includes the selected SD-FD basis pairs/precoded CSI-RS ports, and the corresponding best phase and amplitude for co-phasing the selected pairs/ports. The phase and amplitude for each pair/port are quantized and fed back to the gNB.

In Step 4 illustrated in FIGURE 5D, the gNB implementation algorithm computes the DL precoding matrix per layer based on the selected beams and the corresponding amplitude and phase feedback and performs Physical Downlink Shared Channel (PDSCH) transmission. The transmission is based on the feed-back (PMI) precoding matrices directly (e.g., Single User- MIMO (SU-MIMO) transmission) or the transmission precoding matrix is obtained from an algorithm combining CSI feedback from multiple UEs (MU-MIMO transmission). In this case, a precoder derived based on the precoding matrices (including the CSI reports from co- scheduled UEs) (e.g., Zero-Forcing precoder or regularized ZF precoder). The final precoder is commonly scaled so that the transmit power per power amplifier is not overridden.

Such reciprocity -based transmission can potentially be utilized in a codebook-based DL transmission for FDD in order to, for example, reduce the feedback overhead in UL when NR Type II port-selection codebook is used. Another potential benefit is reduced complexity in the CSI calculation in the UE.

FIGURES 5A-5D only provides one example of the procedure for FDD-based reciprocity operation, where each CSI-RS port contains a single pair of SD-FD basis and UE performs wideband averaging of the channel to obtain the corresponding coefficients. It is possible that each CSI-RS port contains multiple pairs of SD-FD basis and that UE can compress the channel with more Frequency Domain (FD) components besides the DC DFT component.

Type II port selection codebook for FDD operation based on angle and delay reciprocity If the Rel. 16 enhanced Type II port-selection codebook is used for FDD operation based on angle and/or delay reciprocity, the FD basis W? still needs to be determined by the UE. Therefore, in the CSI report, the feedback overhead for indicating which FD basis vectors are selected can be large, especially when M, the number of PMI subbands, is large. Also, the computational complexity at UE for evaluating and selecting the best FD basis vectors also increases as N3 increases. In addition, the channel seen at the UE is frequency-selective, which requires a number of FD basis vectors to compress in the PMI report. Reporting coefficients to these FD basis vectors also consumes a large amount of UL overhead.

Based on the angle and delay reciprocity, as mentioned in the previous section, gNB can determine a set of dominant clusters in the propagation channel by analyzing the angle- delay power spectrum of the UL channel. Then, gNB can utilize this information in a way such that each CSLRS port is precoded towards a dominant cluster. In addition to Spatial Domain (SD) beamforming, each of the CSLRS ports will also be pre-compensated in time such that all the precoded CSLRS ports are aligned in delay domain. As a result, frequency-selectivity of the channel is removed and the UE observes a frequency-flat channel, which requires very small number of FD basis to compress. Ideally, if all the beams can be perfectly aligned in time, UE only needs to do a wideband filtering to obtain all the channel information, based on which UE can calculate the Rel-17 Type II PMI. Even if delay cannot be perfectly pre- compensated at gNB in reality, the frequency selectively seen at the UE can still be greatly reduced, so that UE only requires a much smaller number of FD basis vectors, i.e., the number of basis vectors in Wf , to compress the channel. This procedure is further explained in FIGURE 6, which illustrates an example of CSLRS precoding and Type II PMI calculation based on angle-delay reciprocity.

Based on UL measurement, gNB identifies 8 dominant clusters that exist in the original channel, tagged as A-H, which are distributed in 4 directions, with each direction containing one or multiple taps. In this example, 8 CSLRS ports are precoded at gNB. Each CSLRS port is precoded towards a dominant direction with pre-compensated delay for a given clusters. The delay compensation can be realized in different ways, for instance by applying a linear phase slope across occupied subcarriers. As a result, in the beamformed channel, which is seen at UE, all the dominant clusters are aligned at the same delay, hence the UE only needs to apply a wideband filter (e.g., applying the DC component of a DFT matrix (i.e., Wf containing a single all one vector over frequency domain channel)) to compress the channel and preserve all the channel information. Based on the compressed channel, the UE calculates (selected CSL RS ports) and (complex coefficients for combining selected ports), which are the remaining part of the Type II port selection codebook.

Although the discussion on Rel-17 Type II codebook is still ongoing, the Rel-16 Type II codebook structure has been confirmed to be reused for Rel-17, i.e., the Rel-17 also comprises of One potential difference comparing to the Rel-16 Type II, which is to be discussed in 3GPP, is that might be layer-common. The structure of will remain the same as in Rel-16 Type II.

There currently exist certain challenges, however. For example, when a UE moves with high speed, the channel will vary rapidly. This implies that the CSI report from the UE will be somewhat outdated when it reaches the network. If the network uses this CSI for downlink precoding, the performance will be degraded, as compared to the stationary -UE scenario.

One solution to reduce this problem and cope with such rapid channel variations is to configure faster CSI reporting (i.e., more frequent CSI reporting and measurement). A problem with this approach, however, is that this incurs a large signaling and reporting overhead. Thus, with the current CSI framework in NR it is difficult to obtain accurate CSI for medium-to-high- speed UEs with a reasonable amount of overhead.

SUMMARY

Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, methods and systems are provided that extend UE CSI reporting to also consider channel time variations (e.g., Doppler information) to obtain accurate CSI for medium-to-high-speed UEs. Additionally or alternatively, certain embodiments includes time variations into the CSI report with a reasonable amount of additional overhead.

According to certain embodiments, a method by a UE for reporting CSI feedback includes transmitting to a network node: a CSI report providing CSI for a measured channel and at least one time-domain channel characteristic associated with at least one CSI-RS port selected based on at least one spatial-domain and/or frequency-domain characteristic of the measured channel.

According to certain embodiments, a UE for reporting CSI feedback comprises processing circuitry adapted to transmit to a network node: a CSI report providing CSI for a measured channel, and at least one time-domain channel characteristic associated with at least one CSI-RS port selected based on at least one spatial-domain and/or frequency-domain characteristic of the measured channel.

According to certain embodiments, a method by a network node for receiving CSI feedback includes receiving from a UE: a CSI report providing CSI for a measured channel, and at least one time-domain channel characteristic associated with at least one CSI-RS port selected based on at least one spatial-domain and/or frequency-domain characteristic of the measured channel.

According to certain embodiments, a network node for receiving CSI feedback comprises processing circuitry adapted to receive from a UE: a CSI report providing CSI for a measured channel, and at least one time-domain channel characteristic associated with at least one CSI-RS port selected based on at least one spatial-domain and/or frequency-domain characteristic of the measured channel.

Certain embodiments may provide one or more of the following technical advantage(s). For example, certain embodiments may provide a technical advantage of obtaining accurate CSI for medium-to-high-speed UEs with a reasonable amount of CSI-RS and reporting overhead.

Other advantages may be readily apparent to one having skill in the art. Certain embodiments may have none, some, or all of the recited advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed embodiments and their features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 illustrates a spatial multiplexing operation;

FIGURE 2 illustrates an example of a 4x4 array with dual-polarized antenna elements;

FIGURE 3 illustrates an example of CSI-RS REs for 12 antenna ports;

FIGURE 4 illustrates factorization of the Rel-16 Type II port-selection precoder for a layer /;

FIGURES 5A-5D illustrate an example procedure for reciprocity based FDD transmission scheme;

FIGURE 6 illustrates an example of CSI-RS precoding and Type II PMI calculation based on angle-delay reciprocity;

FIGURE 7 illustrates an example communication system, according to certain embodiments; FIGURE 8 illustrates an example UE, according to certain embodiments;

FIGURE 9 illustrates an example network node, according to certain embodiments;

FIGURE 10 illustrates a block diagram of a host, according to certain embodiments;

FIGURE 11 illustrates a virtualization environment in which functions implemented by some embodiments may be virtualized, according to certain embodiments;

FIGURE 12 illustrates a host communicating via a network node with a UE over a partially wireless connection, according to certain embodiments;

FIGURE 13 illustrates a method by a UE for reporting CSI feedback, according to certain embodiments; and

FIGURE 14 illustrates a method by a network node for receiving CSI feedback, according to certain embodiments.

DETAILED DESCRIPTION

Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

The relative motion between a transmitter and a receiver result in Doppler spread. Under the assumption that the bandwidth of the transmitted signal is very small compared to the carrier frequency f _c , a signal component making an angle of with the direction of motion of the receiver results in a Doppler shift of where v is the relative speed of the receiver, and c is the speed of light in free space. The maximum possible Doppler shift, is obtained when 0 = 0 and n. In case of a multipath propagation, signal components arriving at the receiver from different directions experience different Doppler shifts and the total received signal exhibits a frequency spread around the carrier frequency. The width of the spread around the carrier frequency is referred to as Doppler spread. The precise definition of Doppler spread varies across literature an is often used as an approximation for Doppler spread.

The Doppler characteristics of the received signal is typically captured using the Doppler power spectrum, which is related to the autocorrelation function in time of the time- varying channel through a Fourier transform. Therefore, availability of Doppler power spectrum or its properties allows modeling the time-variations of a channel. Under the assumption of a propagation environment where a receiver is surrounded by infinite scatterers uniformly distributed in a circle, the autocorrelation function in time is a Bessel function of the first kind with as an argument. In this scenario, an estimate of the maximum Doppler shift alone enables us to approximate the autocorrelation in time.

In what follows, the term “Doppler information” means one or many of, e.g., Doppler shift, Doppler spread, and Doppler spectrum. Doppler information can be used to describe the time domain channel characteristics.

According to certain embodiments, solutions are provided for reporting Doppler information which can be used for, e.g., channel prediction at gNB. Doppler information may be reported per selected port. In essence, the proposed solutions provide ways to report Doppler information in conjunction with the Rel-17 Type II CSI report.

For example, according to certain embodiments, the network configures the UE with a CSI report setting (e.g., Type III CSI report) where the CSI report contains a combination of a report associated with a Type II port-selection codebook (that captures the spatial and frequency domain characteristics of the channel measured by the UE) and additional CSI that captures the time-domain characteristics (measured by the UE) of at least two subsets of the reported CSI-RS ports.

In a particular embodiment, each subset contains only one CSI-RS port, i.e., the number of subsets equals the number of selected (and reported) CSI-RS ports.

According to certain embodiments, the UE reports CSI to the network according to the configured report setting. Thus, the CSI report contains a combination of a report associated with a Type II port-selection codebook (that captures the spatial and frequency domain characteristics of the channel measured by the UE) and additional CSI that captures the time- domain characteristics (measured by the UE) of at least two subsets of the reported CSI-RS ports. For example, according to certain embodiments, a method of CSI feedback includes:

The UE receiving configuration of NZP CSI-RS resource(s) for channel measurement, o wherein the configured CSI-RS resource(s) contains at least two CSI- RS occasions of the same CSI-RS port, which does not necessarily span two contiguous symbols, or o wherein the configured CSI-RS resource(s) is limited to one CSI-RS occasion, for which the transmitted waveform contains two (or more) identical parts. The UE receiving configuration for CSI reporting associated with the configured NZP CSI-RS resource(s), wherein the following is configured to be reported in the same report: o Rel-17 Type II CSI report o Time-domain characteristics of the channel

The UE performing channel measurement on the configured CSI-RS resource(s), wherein o A number of CSI-RS ports, which are included in the Rel-17 Type II CSI report, are selected based on the spatial-domain and frequency- domain characteristics of the measured channel. o For each selected CSI-RS port, the time-domain channel characteristics for said port is measured.

The UE reporting the computed CSI report, wherein the following is included o Rel-17 Type II CSI report o Time-domain channel characteristics associated with each selected CSI-RS ports in the Rel-17 Type II CSI report.

In a particular embodiment, the time-domain characteristics of the channel is the Doppler shift associated with each selected CSI-RS port.

In a particular embodiment, the time-domain characteristics of the channel is Doppler shift and Doppler spread associated with each selected CSI-RS port.

In a particular embodiment, the time-domain characteristics of the channel is Doppler shift, Doppler spread and model for Doppler spectrum associated with each selected CSI-RS port.

In a particular embodiment, the time-domain characteristics of the channel is explicit Doppler spectrum (or the time autocorrelation function) associated with each selected CSI-RS port.

In a particular embodiment, the Doppler shift is reported according to a look-up table.

In a particular embodiment, the Doppler shift is normalized against a reference value, and the resulting normalized value is quantized and reported.

In a particular embodiment, a phasor is reported, based on which the Doppler shift can be calculated.

In a particular embodiment, the Doppler spread is reported according to a look-up table.

In a particular embodiment, the model for Doppler power spectrum is pre-defined and indexed, the index for selected model is reported. In a particular embodiment, the Doppler spectrum (or the time autocorrelation function) is quantized and reported.

In a particular embodiment, the time-domain characteristics of the channel is the temporal correlation of the channel, which is described by a basis vector and reported to gNB.

In a particular embodiment, the selected CSI-RS ports and the reported time domain channel characteristics have one-to-one mapping, where the mapping between them can be pre- defined in 3GPP specifications, or the mapping can be inferred through reporting (e.g., by indexing).

In a particular embodiment, the Rel-17 Type II report and time domain channel characteristics are jointly reported in a single CSI report (e.g., named Type III CSI).

According to certain embodiments, a general procedure for channel prediction based on reported Rel-17 Type II CSI and time-domain characteristics such as Doppler information, for example, may include one or more of the following:

• Step 1 : UE transmit reference signals in UL.

• Step 2: gNB estimates and selects a set of dominant clusters (each represented by an angle and delay) by measuring the UL reference signals, and precodes a set of CSI-RS ports towards one of the selected set of dominant clusters with delay being pre-compensated for each selected cluster.

• Step 3 : UE calculates a Rel-17 Type II CSI report (i.e., the port-selection codebook) by selecting a subset of the CSI-RS ports. In addition, for each selected CSI-RS port in the Rel-17 Type II CSI report, UE calculates time domain channel characteristics, e.g., Doppler information, associated with the said port. The Rel-17 Type II CSI report and the associated time domain channel characteristics, e.g., Doppler information, are jointly reported to gNB.

• Step 4: The received Rel-17 Type II CSI report and the associated Doppler information are used for calculating the current and future DL channel, which can be used to compute the current and future PDSCH precoder, until an updated CSI report and Doppler information are received.

Certain embodiments disclosed herein provide reporting mechanism(s) for the Doppler information, which is described as Step 3 above. For example, in Step 3, the Doppler information is calculated for each selected CSI-RS port. Since CSI-RS ports are precoded jointly in the angle-delay domain, where each port covers a unique dominant cluster in the propagation channel, it can be expected that the Doppler components are also quite isolated between CSI-RS ports. In other words, within each CSI-RS port, the Doppler is expected to have much less spread compared to the composite channel.

In some scenarios, Doppler spread within each CSI-RS port is quite small, such that it suffices to model the Doppler as a single Doppler shift, for CSI-RS port i 1, where L is the number of selected CSI-RS ports per polarization.

In some other scenarios, even though Doppler spread is much reduced within a given CSI-RS port, there is still non-negligible amount of Doppler spread. In such cases, it might be useful to also feedback more information regarding the Doppler behavior. For example, both Doppler shift, and Doppler spread, for CSI-RS port i, can be reported. In this way, gNB can utilize both the Doppler shift and Doppler spread for channel prediction. Furthermore, besides feeding back Doppler shift and spread, UE can also feedback a model that describes the characteristic of the Doppler spectrum, for example, a rectangular model where the Doppler spectrum is uniformly distributed between for CSI-RS port i. In some other cases, it might also be beneficial to feedback the complete channel autocorrelation function (or Doppler spectrum).

In a particular embodiment, the time domain channel characteristics in Step 3 is Doppler information, which consists of one or more of the following: a. Doppler shift of the dominant component; b. Doppler shift of the dominant component and Doppler spread; c. Doppler power spectrum by some parameterized model (e.g., rectangular model, exponential model, or Jake’s model); and d. explicit Doppler power spectrum (or time autocorrelation function of the channel).

In a particular embodiment, the value of Doppler shift can be fed back according to some pre-defined look-up table. For example, a table can be defined such that Doppler shift values are divided into a number of non-overlapping groups, and each group is associated with an index. Then, the corresponding index for a certain Doppler shift is reported.

In another particular embodiment, the value of Doppler shift is first normalized with respect to some reference value, and the normalized value is quantized and reported to gNB. The reference value is known to both gNB and UE. For example, the reference value can be either signaled to UE (either directly, or via some look-up table, or via some function that depends on carrier frequency and/or UE velocity), or the reference value can be pre-defined. As another example, the reference value could also be the (fractional part of the) used subcarrier spacing (or a fraction/multiple thereof).

Since the Doppler shift results in a variation in phase, it is sufficient to report the phase change for each selected CSI-RS port if ambiguity can be avoided. The phase change over a period of time At with Doppler shif for CSI-RS port i, is given by

The phase change A is quantized and reported to gNB. Note that the period of time, At, over which is calculated is commonly known to both gNB and UE, which can either be signaled to the UE (either directly, or via some look-up table, or via some function that depends on the subcarrier spacing and/or UE velocity), or can be pre-defined.

In yet another particular embodiment, the value of phase change is quantized (between for example) and reported to gNB.

In another particular embodiment, instead of reporting Doppler shift per selected CSI- RS port, a single Doppler shift may be reported for all the CSI-RS ports. The single Doppler shift can be the average, median, or maximum Doppler shift among the selected CSI-RS ports.

In a particular embodiment, the Doppler spread can be reported according to some pre- defined look-up table.

In a particular embodiment, different models for Doppler power spectrum are indexed, and the index of selected model is reported to gNB.

In a particular embodiment, the Doppler spectrum can be quantized and explicitly reported to the gNB since the time autocorrelation function of the channel is the dual of the Doppler spectrum. In another particular embodiment, the time autocorrelation function of the channel can be quantized and reported.

In a particular embodiment, the time domain channel characteristics in Step 3 can be one or multiple basis vectors that characterize the temporal correlation of the channel. In a particular embodiment, for example, the basis vector can be a DFT vector. The DFT vector that best describes the temporal correlation of the channel is reported to the gNB, in a particular embodiment.

For wideband systems, UE motion results in a scaling of the spectrum instead of a frequency shift. This can be captured by the wideband ambiguity function and/or the wavelet transform. Parameters related to the wideband ambiguity functions and/or wavelet transform can also be reported. In another embodiment, the basis vector can be wavelet(s). The wavelet(s) that best describes the temporal correlation of the channel is reported to gNB.

In a particular embodiment, the selected CSI-RS ports and the reported Doppler information in Step 3 have one-to-one mapping, the association between the selected CSI-RS port and the reported Doppler information is pre-defined or can be inferred in 3GPP specifications (e.g., via indexing).

In a particular embodiment, the reported Rel-17 Type II CSI report and the associated doppler information in Step 3 can be combined and reported in a single CSI report (e.g., named Type III CSI).

FIGURE 7 illustrates an example of a communication system 100 in accordance with some embodiments.

In the example, the communication system 100 includes a telecommunication network 102 that includes an access network 104, such as a radio access network (RAN), and a core network 106, which includes one or more core network nodes 108. The access network 104 includes one or more access network nodes, such as network nodes 110a and 110b (one or more of which may be generally referred to as network nodes 110), or any other similar 3 ^rd Generation Partnership Project (3 GPP) access node or non-3GPP access point. The network nodes 110 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 112a, 112b, 112c, and 112d (one or more of which may be generally referred to as UEs 112) to the core network 106 over one or more wireless connections.

Example wireless communications over a wireless connection include transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 100 may include any number of wired or wireless networks, network nodes, UEs, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections. The communication system 100 may include and/or interface with any type of communication, telecommunication, data, cellular, radio network, and/or other similar type of system.

The UEs 112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and/or operable to communicate wirelessly with the network nodes 110 and other communication devices. Similarly, the network nodes 110 are arranged, capable, configured, and/or operable to communicate directly or indirectly with the UEs 112 and/or with other network nodes or equipment in the telecommunication network 102 to enable and/or provide network access, such as wireless network access, and/or to perform other functions, such as administration in the telecommunication network 102.

In the depicted example, the core network 106 connects the network nodes 110 to one or more hosts, such as host 116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 106 includes one more core network nodes (e.g., core network node 108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and/or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and/or a User Plane Function (UPF).

The host 116 may be under the ownership or control of a service provider other than an operator or provider of the access network 104 and/or the telecommunication network 102, and may be operated by the service provider or on behalf of the service provider. The host 116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio/video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

As a whole, the communication system 100 of FIGURE 7 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

In some examples, the telecommunication network 102 is a cellular network that implements 3 GPP standardized features. Accordingly, the telecommunications network 102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 102. For example, the telecommunications network 102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and/or Massive Machine Type Communication (mMTC)/Massive loT services to yet further UEs.

In some examples, the UEs 112 are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 104. Additionally, a UE may be configured for operating in single- or multi -RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

In the example, the hub 114 communicates with the access network 104 to facilitate indirect communication between one or more UEs (e.g., UE 112c and/or 112d) and network nodes (e.g., network node 110b). In some examples, the hub 114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 114 may be a broadband router enabling access to the core network 106 for the UEs. As another example, the hub 114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 110, or by executable code, script, process, or other instructions in the hub 114. As another example, the hub 114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 114 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 114 then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub 114 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy loT devices. The hub 114 may have a constant/persistent or intermittent connection to the network node 110b. The hub 114 may also allow for a different communication scheme and/or schedule between the hub 114 and UEs (e.g., UE 112c and/or 112d), and between the hub 114 and the core network 106. In other examples, the hub 114 is connected to the core network 106 and/or one or more UEs via a wired connection. Moreover, the hub 114 may be configured to connect to an M2M service provider over the access network 104 and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 110 while still connected via the hub 114 via a wired or wireless connection. In some embodiments, the hub 114 may be a dedicated hub - that is, a hub whose primary function is to route communications to/from the UEs from/to the network node 110b. In other embodiments, the hub 114 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 110b, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

FIGURE 8 shows a UE 200 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and/or operable to communicate wirelessly with network nodes and/or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle-mounted or vehicle embedded/integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and/or an enhanced MTC (eMTC) UE.

A UE may support device-to-device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), orvehicle- to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and/or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

The UE 200 includes processing circuitry 202 that is operatively coupled via a bus 204 to an input/output interface 206, a power source 208, a memory 210, a communication interface 212, and/or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in FIGURE 8. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

The processing circuitry 202 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 210. The processing circuitry 202 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 202 may include multiple central processing units (CPUs).

In the example, the input/output interface 206 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and/or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

In some embodiments, the power source 208 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 208 may further include power circuitry for delivering power from the power source 208 itself, and/or an external power source, to the various parts of the UE 200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 208 to make the power suitable for the respective components of the UE 200 to which power is supplied.

The memory 210 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 210 includes one or more application programs 214, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 216. The memory 210 may store, for use by the UE 200, any of a variety of various operating systems or combinations of operating systems.

The memory 210 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and/or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘ SIM card.’ The memory 210 may allow the UE 200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 210, which may be or comprise a device-readable storage medium.

The processing circuitry 202 may be configured to communicate with an access network or other network using the communication interface 212. The communication interface 212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 222. The communication interface 212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 218 and/or a receiver 220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 218 and receiver 220 may be coupled to one or more antennas (e.g., antenna 222) and may share circuit components, software or firmware, or alternatively be implemented separately.

In the illustrated embodiment, communication functions of the communication interface 212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and/or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol/internet protocol (TCP/IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input. A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door/window sensor, a flood/moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and/or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 200 shown in FIGURE 8.

As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another UE and/or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3 GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and/or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators. FIGURE 9 shows a network node 300 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and/or operable to communicate directly or indirectly with a UE and/or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)).

Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units and/or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell/multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and/or Minimization of Drive Tests (MDTs).

The network node 300 includes a processing circuitry 302, a memory 304, a communication interface 306, and a power source 308. The network node 300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 304 for different RATs) and some components may be reused (e.g., a same antenna 310 may be shared by different RATs). The network node 300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 300.

The processing circuitry 302 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node 300 components, such as the memory 304, to provide network node 300 functionality.

In some embodiments, the processing circuitry 302 includes a system on a chip (SOC). In some embodiments, the processing circuitry 302 includes one or more of radio frequency (RF) transceiver circuitry 312 and baseband processing circuitry 314. In some embodiments, the radio frequency (RF) transceiver circuitry 312 and the baseband processing circuitry 314 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 312 and baseband processing circuitry 314 may be on the same chip or set of chips, boards, or units.

The memory 304 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device-readable and/or computer-executable memory devices that store information, data, and/or instructions that may be used by the processing circuitry 302. The memory 304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and/or other instructions capable of being executed by the processing circuitry 302 and utilized by the network node 300. The memory 304 may be used to store any calculations made by the processing circuitry 302 and/or any data received via the communication interface 306. In some embodiments, the processing circuitry 302 and memory 304 is integrated. The communication interface 306 is used in wired or wireless communication of signaling and/or data between a network node, access network, and/or UE. As illustrated, the communication interface 306 comprises port(s)/terminal(s) 316 to send and receive data, for example to and from a network over a wired connection. The communication interface 306 also includes radio front-end circuitry 318 that may be coupled to, or in certain embodiments a part of, the antenna 310. Radio front-end circuitry 318 comprises filters 320 and amplifiers 322. The radio front-end circuitry 318 may be connected to an antenna 310 and processing circuitry 302. The radio front-end circuitry may be configured to condition signals communicated between antenna 310 and processing circuitry 302. The radio front-end circuitry 318 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 320 and/or amplifiers 322. The radio signal may then be transmitted via the antenna 310. Similarly, when receiving data, the antenna 310 may collect radio signals which are then converted into digital data by the radio front-end circuitry 318. The digital data may be passed to the processing circuitry 302. In other embodiments, the communication interface may comprise different components and/or different combinations of components.

In certain alternative embodiments, the network node 300 does not include separate radio front-end circuitry 318, instead, the processing circuitry 302 includes radio front-end circuitry and is connected to the antenna 310. Similarly, in some embodiments, all or some of the RF transceiver circuitry 312 is part of the communication interface 306. In still other embodiments, the communication interface 306 includes one or more ports or terminals 316, the radio front-end circuitry 318, and the RF transceiver circuitry 312, as part of a radio unit (not shown), and the communication interface 306 communicates with the baseband processing circuitry 314, which is part of a digital unit (not shown).

The antenna 310 may include one or more antennas, or antenna arrays, configured to send and/or receive wireless signals. The antenna 310 may be coupled to the radio front-end circuitry 318 and may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In certain embodiments, the antenna 310 is separate from the network node 300 and connectable to the network node 300 through an interface or port.

The antenna 310, communication interface 306, and/or the processing circuitry 302 may be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by the network node. Any information, data and/or signals may be received from a UE, another network node and/or any other network equipment. Similarly, the antenna 310, the communication interface 306, and/or the processing circuitry 302 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and/or signals may be transmitted to a UE, another network node and/or any other network equipment.

The power source 308 provides power to the various components of network node 300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 308 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 300 with power for performing the functionality described herein. For example, the network node 300 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 308. As a further example, the power source 308 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

Embodiments of the network node 300 may include additional components beyond those shown in FIGURE 9 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and/or any functionality necessary to support the subject matter described herein. For example, the network node 300 may include user interface equipment to allow input of information into the network node 300 and to allow output of information from the network node 300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 300.

FIGURE 10 is a block diagram of a host 400, which may be an embodiment of the host 116 of FIGURE 7, according to certain embodiments. As used herein, the host 400 may be or comprise various combinations hardware and/or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host 400 may provide one or more services to one or more UEs.

The host 400 includes processing circuitry 402 that is operatively coupled via a bus 404 to an input/output interface 406, a network interface 408, a power source 410, and a memory 412. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 2 and 3, such that the descriptions thereof are generally applicable to the corresponding components of host 400. The memory 412 may include one or more computer programs including one or more host application programs 414 and data 416, which may include user data, e.g., data generated by a UE for the host 400 or data generated by the host 400 for a UE. Embodiments of the host 400 may utilize only a subset or all of the components shown. The host application programs 414 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application programs 414 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host 400 may select and/or indicate a different host for over-the-top services for a UE. The host application programs 414 may support various protocols, such as the HTTP Live Streaming (EILS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), etc.

FIGURE 11 is a block diagram illustrating a virtualization environment 500 in which functions implemented by some embodiments may be virtualized.

In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 500 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized.

Applications 502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein.

Hardware 504 includes processing circuitry, memory that stores software and/or instructions executable by hardware processing circuitry, and/or other hardware devices as described herein, such as a network interface, input/output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 508a and 508b (one or more of which may be generally referred to as VMs 508), and/or perform any of the functions, features and/or benefits described in relation with some embodiments described herein. The virtualization layer 506 may present a virtual operating platform that appears like networking hardware to the VMs 508.

The VMs 508 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 506. Different embodiments of the instance of a virtual appliance 502 may be implemented on one or more of VMs 508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

In the context of NFV, a VM 508 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 508, and that part of hardware 504 that executes that VM, be it hardware dedicated to that VM and/or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 508 on top of the hardware 504 and corresponds to the application 502.

Hardware 504 may be implemented in a standalone network node with generic or specific components. Hardware 504 may implement some functions via virtualization. Alternatively, hardware 504 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 510, which, among others, oversees lifecycle management of applications 502. In some embodiments, hardware 504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 512 which may alternatively be used for communication between hardware nodes and radio units. FIGURE 12 shows a communication diagram of a host 602 communicating via a network node 604 with a UE 606 over a partially wireless connection in accordance with some embodiments.

Example implementations, in accordance with various embodiments, of the UE (such as a UE 112a of FIGURE 7 and/or UE 200 of FIGURE 8), network node (such as network node 110a of FIGURE 7 and/or network node 300 of FIGURE 9), and host (such as host 116 of FIGURE 7 and/or host 400 of FIGURE 10) discussed in the preceding paragraphs will now be described with reference to FIGURE 12.

Like host 400, embodiments of host 602 include hardware, such as a communication interface, processing circuitry, and memory. The host 602 also includes software, which is stored in or accessible by the host 602 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE 606 connecting via an over-the-top (OTT) connection 650 extending between the UE 606 and host 602. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 650.

The network node 604 includes hardware enabling it to communicate with the host 602 and UE 606. The connection 660 may be direct or pass through a core network (like core network 106 of FIGURE 7) and/or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

The UE 606 includes hardware and software, which is stored in or accessible by UE 606 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE 606 with the support of the host 602. In the host 602, an executing host application may communicate with the executing client application via the OTT connection 650 terminating at the UE 606 and host 602. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection 650 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection 650.

The OTT connection 650 may extend via a connection 660 between the host 602 and the network node 604 and via a wireless connection 670 between the network node 604 and the UE 606 to provide the connection between the host 602 and the UE 606. The connection 660 and wireless connection 670, over which the OTT connection 650 may be provided, have been drawn abstractly to illustrate the communication between the host 602 and the UE 606 via the network node 604, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

As an example of transmitting data via the OTT connection 650, in step 608, the host 602 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE 606. In other embodiments, the user data is associated with a UE 606 that shares data with the host 602 without explicit human interaction. In step 610, the host 602 initiates a transmission carrying the user data towards the UE 606. The host 602 may initiate the transmission responsive to a request transmitted by the UE 606. The request may be caused by human interaction with the UE 606 or by operation of the client application executing on the UE 606. The transmission may pass via the network node 604, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 612, the network node 604 transmits to the UE 606 the user data that was carried in the transmission that the host 602 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 614, the UE 606 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 606 associated with the host application executed by the host 602.

In some examples, the UE 606 executes a client application which provides user data to the host 602. The user data may be provided in reaction or response to the data received from the host 602. Accordingly, in step 616, the UE 606 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input/output interface of the UE 606. Regardless of the specific manner in which the user data was provided, the UE 606 initiates, in step 618, transmission of the user data towards the host 602 via the network node 604. In step 620, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 604 receives user data from the UE 606 and initiates transmission of the received user data towards the host 602. In step 622, the host 602 receives the user data carried in the transmission initiated by the UE 606.

One or more of the various embodiments improve the performance of OTT services provided to the UE 606 using the OTT connection 650, in which the wireless connection 670 forms the last segment. More precisely, the teachings of these embodiments may improve one or more of, for example, data rate, latency, and/or power consumption and, thereby, provide benefits such as, for example, reduced user waiting time, relaxed restriction on file size, improved content resolution, better responsiveness, and/or extended battery lifetime.

In an example scenario, factory status information may be collected and analyzed by the host 602. As another example, the host 602 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 602 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 602 may store surveillance video uploaded by a UE. As another example, the host 602 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host 602 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and/or transmitting data.

In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 650 between the host 602 and UE 606, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host 602 and/or UE 606. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 650 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 650 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node 604. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host 602. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 650 while monitoring propagation times, errors, etc.

Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and/or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer- readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and/or by end users and a wireless network generally.

FIGURE 13 illustrates a method 700 by a UE for reporting CSI feedback, according to certain embodiments. The method includes, at step 702, the UE 112 transmitting to a network node 110: a CSI report providing CSI for a measured channel, and • at least one time-domain channel characteristic associated with at least one CSI- RS port selected based on at least one spatial-domain and/or frequency-domain characteristic of the measured channel.

In a particular embodiment, the at least one time-domain channel characteristic and the CSI for the measured channel is transmitted in a single CSI report.

In a particular embodiment, the CSI report comprises a Type II port selection codebook.

In a particular embodiment, the at least one time-domain characteristic of the channel indicates at least one basis vector. In a further particular embodiment, a basis vector is a DFT vector.

In a particular embodiment, each basis vector is associated with an associated temporal correlation of the channel.

In a particular embodiment, the at least one time-domain characteristic of the channel is an explicit Doppler spectrum associated with each CSI-RS port.

In a particular embodiment, the Doppler spectrum is quantized by the wireless device.

In a particular embodiment, the at least one time-domain characteristic of the channel is at least one of: a Doppler shift associated with each CSI-RS port, a Doppler spread associated with each CSI-RS port, and a model for a Doppler spectrum associated with each CSI-RS port. In a further particular embodiment, at least one of the Doppler shift, the Doppler spread, and the model for the Doppler spectrum is reported according to a look-up table. In another further particular embodiment, the Doppler shift has been normalized against a reference value and quantized. In another particular embodiment, at least one of the Doppler shift, the Doppler spread, and the model for the Doppler spectrum is reported according to an index.

In a particular embodiment, the at least one time-domain characteristic of the channel comprises a phasor for calculating a Doppler shift by the network node.

In a particular embodiment, the CSI for the measured channel is associated with at least one CSI-RS resource, and the at least one CSI-RS resource comprises: at least two CSI-RS occasions of the same CSI-RS port, or one CSI-RS occasion, for which the transmitted waveform contains two (or more) identical parts.

In a particular embodiment, the UE 112 selects the at least one CSI-RS port based on the at least one spatial-domain and/or frequency-domain characteristic of the measured channel, and the UE 112 measures the at least one time-domain channel characteristic for each CSI-RS port.

In a particular embodiment, the at least one CSI-RS port and the at least one time domain channel characteristic have a one-to-one mapping. In a particular embodiment, the UE 112 receives, from the network node 110, the at least one CSI-RS port, and wherein the at least one CSI-RS port comprises a set of CSI-RS ports.

FIGURE 14 illustrates a method 800 by a network node for receiving CSI feedback, according to certain embodiments. The method includes, at step 802, the network node receiving from a UE:

• a CSI report providing CSI for a measured channel, and

• at least one time-domain channel characteristic associated with at least one CSI- RS port selected based on at least one spatial-domain and/or frequency-domain characteristic of the measured channel.

In a particular embodiment, the at least one time-domain channel characteristic and the CSI for the measured channel is transmitted in a single CSI report.

In a particular embodiment, the CSI report comprises a Type II port selection codebook.

In a particular embodiment, the at least one time-domain characteristic of the channel indicates at least one basis vector. In a further particular embodiment, a basis vector is a DFT vector.

In a particular embodiment, each basis vector is associated with an associated temporal correlation of the channel.

In a particular embodiment, the at least one time-domain characteristic of the channel is an explicit Doppler spectrum associated with each CSI-RS port.

In a particular embodiment, the Doppler spectrum is quantized by the wireless device.

In a particular embodiment, the at least one time-domain characteristic of the channel is at least one of: a Doppler shift associated with each CSI-RS port, a Doppler spread associated with each CSI-RS port, and a model for a Doppler spectrum associated with each CSI-RS port. In a further particular embodiment, at least one of the Doppler shift, the Doppler spread, and the model for the Doppler spectrum is reported according to a look-up table. In another further particular embodiment, the Doppler shift has been normalized against a reference value and quantized. In another particular embodiment, at least one of the Doppler shift, the Doppler spread, and the model for the Doppler spectrum is reported according to an index.

In a particular embodiment, the at least one time-domain characteristic of the channel comprises a phasor for calculating a Doppler shift by the network node.

In a particular embodiment, the CSI for the measured channel is associated with at least one CSI-RS resource, and the at least one CSI-RS resource comprises: at least two CSI-RS occasions of the same CSI-RS port, or one CSI-RS occasion, for which the transmitted waveform contains two (or more) identical parts.

In a particular embodiment, the network node 110 transmits information indicating the at least one CSI-RS resource to the UE 112.

In a particular embodiment, prior to receiving the CSI report and the at least one time- domain channel characteristic, the network node 110 receives at least one reference signal from the UE 112. The network node 110 performs at least one measurement of the at least one reference signal and selects the at least one CSI-RS port based on the at least one measurement. The network node 110 transmits information indicating the at least one CSI-RS port to the UE 112.

In a particular embodiment, the at least one CSI-RS port is associated with a dominant cluster represented by an angle and a delay associated with the at least one reference signal received from the UE.

In a particular embodiment, the network node 110 selects the at least one CSI-RS port based on the at least one spatial-domain and/or frequency-domain characteristic of the measured channel. The network node 110 transmits information indicating the at least one CSI-RS port to the UE 112.

In a particular embodiment, the at least one CSI-RS port and the at least one time domain channel characteristic have a one-to-one mapping.

In a particular embodiment, the network node 110 transmits, to the UE 112, information indicating the at least one CSI-RS port, and wherein the at least one CSI-RS port comprises a set of CSI-RS ports.

EXAMPLE EMBODIMENTS

Group A Example Embodiments

Example Embodiment Al . A method by a user equipment for reporting CSI feedback, the method comprising: any of the user equipment steps, features, or functions described above, either alone or in combination with other steps, features, or functions described above.

Example Embodiment A2. The method of the previous embodiment, further comprising one or more additional user equipment steps, features or functions described above.

Example Embodiment A3. The method of any of the previous embodiments, further comprising: providing user data; and forwarding the user data to a host computer via the transmission to the network node. Group B Example Embodiments

Example Embodiment Bl. A method performed by a network node for receiving CSI feedback, the method comprising: any of the network node steps, features, or functions described above, either alone or in combination with other steps, features, or functions described above.

Example Embodiment B2. The method of the previous embodiment, further comprising one or more additional network node steps, features or functions described above.

Example Embodiment B3. The method of any of the previous embodiments, further comprising: obtaining user data; and forwarding the user data to a host or a user equipment.

Group C Example Embodiments

Example Embodiment Cl . A method by a UE for reporting CSI feedback, the method comprising: transmitting to a network node: a CSI report providing CSI for a measured channel, and at least one time-domain channel characteristic associated with at least one CSI-RS port selected based on at least one spatial-domain and/or frequency-domain characteristic of the measured channel.

Example Embodiment C2. The method of Example Embodiment Cl, wherein: the CSI for the measured channel is associated with at least one CSI-RS resource, and the at least one CSI-RS resource comprises: at least two CSI-RS occasions of the same CSI-RS port, or one CSI-RS occasion, for which the transmitted waveform contains two (or more) identical parts.

Example Embodiment C3. The method of any one of Example Embodiments Cl to C2, wherein the CSI report comprises a Release 17 Type II CSI report.

Example Embodiment C4. The method of any one of Example Embodiments Cl to C3, further comprising: selecting the at least one CSI-RS port based on the at least one spatial- domain and/or frequency-domain characteristic of the measured channel; and measuring the at least one time-domain channel characteristic for each CSI-RS port.

Example Embodiment C5. The method of any one of Example Embodiments Cl to C4, wherein the at least one time-domain characteristic of the channel is a Doppler shift associated with each CSI-RS port.

Example Embodiment C6. The method of any one of Example Embodiments Cl to C4, wherein the at least one time-domain characteristic of the channel is a Doppler shift and a Doppler spread associated with each CSI-RS port. Example Embodiment C7. The method of any one of Example Embodiments Cl to C4, wherein the at least one time-domain characteristic of the channel is a Doppler shift, a Doppler spread, and a model for a Doppler spectrum associated with each CSI-RS port.

Example Embodiment C8. The method of any one of Example Embodiments C5 to C7, wherein the Doppler shift is reported according to a look-up table.

Example Embodiment C9. The method of any one of Example Embodiments C5 to C8, wherein the Doppler shift is normalized against a reference value, and the resulting normalized value is quantized and reported.

Example Embodiment CIO. The method of any one of Example Embodiments C5 to C9, wherein the Doppler spread is reported according to a look-up table.

Example Embodiment Cl 1. The method of any one of Example Embodiments C7 to C9, wherein the Doppler spectrum is reported according to an index associated with a selected model.

Example Embodiment C12. The method of any one of Example Embodiments Cl to C4, wherein the at least one time-domain characteristic of the channel comprises a phasor for calculating a Doppler shift by the network node.

Example Embodiment Cl 3. The method of any one of Example Embodiments Cl to C4, wherein the at least one time-domain characteristic of the channel is an explicit Doppler spectrum (or the time autocorrelation function) associated with each CSI-RS port.

Example Embodiment C14. The method of Example Embodiment C13, wherein the Doppler spectrum (or the time autocorrelation function) is quantized by the wireless device.

Example Embodiment Cl 5. The method of any one of Example Embodiments Cl to C14, wherein the at least one time-domain characteristic of the channel comprises a basis vector, the basis vector being associated with a temporal correlation of the channel.

Example Embodiment Cl 6. The method of any one of Example Embodiments Cl to Cl 5, wherein the at least one CSI-RS port and the at least one time domain channel characteristic have a one-to-one mapping.

Example Embodiment Cl 7. The method of any one of Example Embodiments Cl to Cl 6, wherein the at least one time-domain channel characteristic and the CSI for the measured channel is transmitted in a single CSI report.

Example Embodiment Cl 8. The method of any one of Example Embodiments Cl to Cl 7, further comprising receiving, from the network node, the at least one CSI-RS port, and wherein the at least one CSI-RS port comprises a set of CSI-RS ports. Example Embodiment Cl 9. The method of Example Embodiments Cl to Cl 8, further comprising: providing user data; and forwarding the user data to a host via the transmission to the network node.

Example Embodiment C20. A user equipment comprising processing circuitry configured to perform any of the methods of Example Embodiments Cl to Cl 9.

Example Embodiment C21.A user equipment adapted to perform any of the methods of Example Embodiments Cl to Cl 9.

Example Embodiment C22. A computer program comprising instructions which when executed on a computer perform any of the methods of Example Embodiments Cl to C19.

Example Embodiment C23. A computer program product comprising computer program, the computer program comprising instructions which when executed on a computer perform any of the methods of Example Embodiments Cl to Cl 9.

Example Embodiment C24. A non-transitory computer readable medium storing instructions which when executed by a computer perform any of the methods of Example Embodiments Cl to Cl 9.

Group D Example Embodiments

Example Embodiment DI. A method by a network node for receiving CSI feedback, the method comprising: receiving from a UE: a CSI report providing CSI for a measured channel, and at least one time-domain channel characteristic associated with at least one CSI- RS port selected based on at least one spatial -domain and/or frequency-domain characteristic of the measured channel.

Example Embodiment D2. The method of Example Embodiment DI, wherein: the CSI for the measured channel is associated with at least one CSI-RS resource, and the at least one CSI-RS resource comprises: at least two CSI-RS occasions of the same CSI-RS port, or one CSI-RS occasion, for which the transmitted waveform contains two (or more) identical parts.

Example Embodiment D3. The method of Example Embodiment D2, further comprising transmitting information indicating the at least one CSI-RS resource to the UE.

Example Embodiment D4. The method of any one of Example Embodiments DI to D3, wherein prior to receiving the CSI report and the at least one time-domain channel characteristic, the method comprises: receiving at least one reference signal from the UE; and performing at least one measurement of the at least one reference signal; and selecting the at least one CSI-RS port based on the at least one measurement; and transmitting information indicating the at least one CSI-RS port to the UE.

Example Embodiment D5. The method of Example Emboidment D4, wherein the at least one CSI-RS port is associated with a dominant cluster represented by an angle and a delay associated with the at least one reference signal received from the UE.

Example Embodiment D6. The method of any one of Example Embodiments DI to D5, wherein the CSI report comprises a Release 17 Type II CSI report.

Example Embodiment D7. The method of any one of Example Embodiments DI to D6, further comprising: selecting the at least one CSI-RS port based on the at least one spatial- domain and/or frequency-domain characteristic of the measured channel; and transmitting information indicating the at least one CSI-RS port to the UE.

Example Embodiment D8. The method of any one of Example Embodiments DI to D7, wherein the at least one time-domain characteristic of the channel is a Doppler shift associated with each CSI-RS port.

Example Embodiment D9. The method of any one of Example Embodiments DI to D8, wherein the at least one time-domain characteristic of the channel is a Doppler shift and a Doppler spread associated with each CSI-RS port.

Example Embodiment DIO. The method of any one of Example Embodiments DI to D8, wherein the at least one time-domain characteristic of the channel is a Doppler shift, a Doppler spread, and a model for a Doppler spectrum associated with each CSI-RS port.

Example Embodiment DI 1. The method of any one of Example Embodiments D8 to DIO, wherein the Doppler shift is reported according to a look-up table.

Example Embodiment D 12. The method of any one of Example Embodiments

D8 to Dl l, wherein the Doppler shift is normalized against a reference value, and the resulting normalized value is quantized and reported.

Example Embodiment D 13. The method of any one of Example Embodiments

D9 to D12, wherein the Doppler spread is reported according to a look-up table.

Example Embodiment D 14. The method of any one of Example Embodiments

DIO to D13, wherein the Doppler spectrum is reported according to an index associated with a selected model.

Example Embodiment DI 5. The method of any one of Example Embodiments

DI to D8, wherein the at least one time-domain characteristic of the channel comprises a phasor for calculating a Doppler shift by the network node. Example Embodiment D16. The method of any one of Example Embodiments DI to D8, wherein the at least one time-domain characteristic of the channel is an explicit Doppler spectrum (or the time autocorrelation function) associated with each CSI-RS port.

Example Embodiment DI 7. The method of Example Embodiment DI 6, wherein the Doppler spectrum (or the time autocorrelation function) is quantized by the wireless device.

Example Embodiment DI 8. The method of any one of Example Embodiments DI to DI 7, wherein the at least one time-domain characteristic of the channel comprises a basis vector, the basis vector being associated with a temporal correlation of the channel.

Example Embodiment D19. The method of any one of Example Embodiments DI to DI 8, wherein the at least one CSI-RS port and the at least one time domain channel characteristic have a one-to-one mapping.

Example Embodiment D20. The method of any one of Example Embodiments DI to DI 9, wherein the at least one time-domain channel characteristic and the CSI for the measured channel is transmitted in a single CSI report.

Example Embodiment D21. The method of any one of Example Embodiments DI to D20, further comprising transmitting, to the UE, information indicating the at least one CSI- RS port, and wherein the at least one CSI-RS port comprises a set of CSI-RS ports.

Example Embodiment D22. A network node comprising processing circuitry configured to perform any of the methods of Example Embodiments DI to D21.

Example Embodiment D23. A network node adapted to perform any of the methods of Example Embodiments DI to D21.

Example Embodiment D24. A computer program comprising instructions which when executed on a computer perform any of the methods of Example Embodiments DI to D21.

Example Embodiment D25. A computer program product comprising computer program, the computer program comprising instructions which when executed on a computer perform any of the methods of Example Embodiments DI to D21.

Example Embodiment D26. A non-transitory computer readable medium storing instructions which when executed by a computer perform any of the methods of Example Embodiments DI to D21.

Group E Example Embodiments

Example Embodiment El . A user equipment for reporting CSI feedback, comprising: processing circuitry configured to perform any of the steps of any of the Group A and C Example Embodiments; and power supply circuitry configured to supply power to the processing circuitry.

Example Embodiment E2. A network node for receiving Channel State Information (CSI) feedback, the network node comprising: processing circuitry configured to perform any of the steps of any of the Group B and D Example Embodiments; power supply circuitry configured to supply power to the processing circuitry.

Example Embodiment E3. A UE reporting CSI feedback, the UE comprising: an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; the processing circuitry being configured to perform any of the steps of any of the Group A and C Example Embodiments; an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE.

Example Embodiment E4. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: processing circuitry configured to provide user data; and a network interface configured to initiate transmission of the user data to a cellular network for transmission to a UE, wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform any of the steps of any of the Group A and C Example Embodiments to receive the user data from the host.

Example Embodiment E5. The host of the previous Example Embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data to the UE from the host.

Example Embodiment E6. The host of the previous 2 Example Embodiments, wherein: the processing circuitry of the host is configured to execute a host application, thereby providing the user data; and the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

Example Embodiment E7. A method implemented by a host operating in a communication system that further includes a network node and a UE, the method comprising: providing user data for the UE; and initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the UE performs any of the operations of any of the Group A embodiments to receive the user data from the host.

Example Emboidment E8. The method of the previous Example Embodiment, further comprising: at the host, executing a host application associated with a client application executing on the UE to receive the user data from the UE.

Example Embodiment E9. The method of the previous Example Embodiment, further comprising: at the host, transmitting input data to the client application executing on the UE, the input data being provided by executing the host application, wherein the user data is provided by the client application in response to the input data from the host application.

Example Emboidment E10. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: processing circuitry configured to provide user data; and a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE), wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform any of the steps of any of the Group A and C Example Embodiments to transmit the user data to the host.

Example Emboidment El l. The host of the previous Example Embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data from the UE to the host.

Example Embodiment E12. The host of the previous 2 Example Embodiments, wherein: the processing circuitry of the host is configured to execute a host application, thereby providing the user data; and the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

Example Embodiment El 3. A method implemented by a host configured to operate in a communication system that further includes a network node and a user equipment (UE), the method comprising: at the host, receiving user data transmitted to the host via the network node by the UE, wherein the UE performs any of the steps of any of the Group A and C Example Embodiments to transmit the user data to the host.

Example Embodiment E14. The method of the previous Example Embodiment, further comprising: at the host, executing a host application associated with a client application executing on the UE to receive the user data from the UE.

Example Embodiment El 5. The method of the previous Example Embodiment, further comprising: at the host, transmitting input data to the client application executing on the UE, the input data being provided by executing the host application, wherein the user data is provided by the client application in response to the input data from the host application.

Example Embodiment E16. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: processing circuitry configured to provide user data; and a network interface configured to initiate transmission of the user data to a network node in a cellular network for transmission to a UE, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B and D Example Embodiments to transmit the user data from the host to the UE.

Example Embodiment E17. The host of the previous Example Embodiment, wherein: the processing circuitry of the host is configured to execute a host application that provides the user data; and the UE comprises processing circuitry configured to execute a client application associated with the host application to receive the transmission of user data from the host.

Example Embodiment E18. A method implemented in a host configured to operate in a communication system that further includes a network node and a UE, the method comprising: providing user data for the UE; and initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the network node performs any of the operations of any of the Group B and D Example Embodiments to transmit the user data from the host to the UE.

Example Embodiment E19. The method of the previous Example Embodiment, further comprising, at the network node, transmitting the user data provided by the host for the UE.

Example Emboidment E20. The method of any of the previous 2 Example Embodiments, wherein the user data is provided at the host by executing a host application that interacts with a client application executing on the UE, the client application being associated with the host application.

Example Embodiment E21. A communication system configured to provide an over- the-top service, the communication system comprising: a host comprising: processing circuitry configured to provide user data for a user equipment (UE), the user data being associated with the over-the-top service; and a network interface configured to initiate transmission of the user data toward a cellular network node for transmission to the UE, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B and D Example Embodiments to transmit the user data from the host to the UE.

Example Embodiment E22. The communication system of the previous Example Embodiment, further comprising: the network node; and/or the user equipment.

Example Embodiment E23. A host configured to operate in a communication system to provide an OTT service, the host comprising: processing circuitry configured to initiate receipt of user data; and a network interface configured to receive the user data from a network node in a cellular network, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B and D Example Embodiments to receive the user data from a UE for the host.

Example Embodiment E24. The host of the previous 2 Example Embodiments, wherein: the processing circuitry of the host is configured to execute a host application, thereby providing the user data; and the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

Example Embodiment E25. The host of the any of the previous 2 Example Embodiments, wherein the initiating receipt of the user data comprises requesting the user data.

Example Embodiment E26. A method implemented by a host configured to operate in a communication system that further includes a network node and a UE, the method comprising: at the host, initiating receipt of user data from the UE, the user data originating from a transmission which the network node has received from the UE, wherein the network node performs any of the steps of any of the Group B and D Example Embodiments to receive the user data from the UE for the host.

Example Embodiment E27. The method of the previous Example Embodiment, further comprising at the network node, transmitting the received user data to the host.