Methods of pmi generation for large arrays

Abstract

Systems and methods for Precoding Matrix Indicator (PMI) generation for large arrays are provided. In some embodiments, a User Equipment (UE): determines a first 2-dimensional Discrete Fourier Transform (DFT) vector applied to a first antenna group with N 1 ports in a first dimension and N 2 ports in the second dimension; determines an inter-antenna group co-phasing factor along with a second 2-dimensional DFT vector applied to a second antenna group with N 1 ports in a first dimension and N 2 ports in the second dimension; and reports the first 2-dimensional DFT vector, the second 2-dimentional DFT vector, and the inter-antenna group co- phasing factor to a network node as part of precoder matrix indicator feedback. When the orthogonal vector to be applied to a second layer is determined through predefined offsets, no additional bits are needed to indicate the orthogonal vector to be applied. Hence, inter-layer interference is reduced without additional feedback overhead.

Description

METHODS OF PMI GENERATION FOR LARGE ARRAYSRELATED APPLICATIONS

[0001] This application claims the benefit of provisional patent application serial number 63 / 516,472, filed July 28, 2023, the disclosure of which is hereby incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to Channel State Information (CSI) feedback.BACKGROUND

[0003] Codebook-based precoding

[0004] 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 multipleinput multiple-output (MIMO) communication channel. Such systems and / or related techniques are commonly referred to as MIMO.

[0005] A core component of the fifth Generation (5G) wireless network or New Radio (NR) is the support of MIMO antenna deployments and MIMO related techniques such as spatial multiplexing. Spatial multiplexing can be used to increase data rates in favorable channel conditions. Figure 1 shows an example of spatial multiplexing. An information carrying symbol vector s is multiplied by an NTX r precoding matrix or precoder W, which serves to distribute the transmit energy in a subspace of the NTdimensional vector space. The precoding matrix is typically selected from a codebook of possible precoding matrices, and typically indicated by means of a Precoding Matrix Indicator (PMI), which specifies a unique precoding matrix in the codebook for a given number of symbol streams. The r symbols in s each correspond to a MIMO layer and r is referred to as the transmission rank, which equals to the number of columns of the precoder W. In this way, spatial multiplexing is achieved since multiple symbols can be transmitted simultaneously over the same time / frequency resource element (RE). The number of symbols r is typically adapted to suit the current channel properties.

[0006] NR uses Orthogonal Frequency Division Multiplexing (OFDM) in downlink. The received NRX lvector ynat a UE on a certain RE can be expressed as:where enis a receiver noise / interference vector. The precoder W can be constant over frequency (i.e., wideband), or frequency selective (i.e., per subband).

[0007] The precoder W is chosen to match the characteristics of the NRX NTMIMO channel matrix Hn, resulting in so-called channel dependent precoding. This is also commonly referred to as closed-loop precoding.

[0008] In closed-loop precoding, the UE feeds back recommendations on a suitable precoder to the gNB in the form of a PMI based on downlink channel measurements. For that purpose, the UE is configured with a Channel State Information (CSI) report configuration including CSI Reference Signals (CSI-RS) for channel measurements and a codebook of candidate precoders. In addition to precoders, the feedback may also include a Rank Indicator (RI) and one or two Channel Quality Indicators (CQIs). RI, PMI and CQI are part of a CSI feedback. 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 Physical Resource Blocks (PRBs) ranging between 4-32 PRBs depending on the Bandwidth Part (BWP) size.

[0009] 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).

[0010] 2D Antenna arrays

[0011] Two-dimensional antenna arrays are widely used and such antenna arrays can be described by a number of antenna ports, Nr, in a first dimension (e.g., the horizontal dimension), a number of antenna ports, N2, in the second dimension perpendicular to the first dimension (e.g., the vertical dimension), and a number of polarizations Np. The total number of antenna ports is thus N = N1N2Np. The concept of an antenna port is non-limiting in the sense that it can refer to any virtualization (e.g., linear mapping) to the physical antenna elements. For example, pairs of physical antenna elements could be fed the same signal, and hence share the same virtualized antenna port.

[0012] An example of a 4 X 4 (i.e., N1X N2l) array with dual-polarized antenna elements (i.e., Np= 2) is illustrated in Figure 2.

[0013] Precoding may be interpreted as multiplying the signal to be transmitted by a set of beamforming weights on the antenna ports prior to transmission. A typical approach is to tailorthe precoder to the antenna form factor, i.e., taking into account NltN2and Npwhen designing the precoder codebook.

[0014] Channel State Information Reference Signals (CSI-RS)

[0015] For CSI measurement and feedback, CSI-RS are defined. A CSI-RS is transmitted on an antenna port at the gNB and is used by a UE to measure downlink channel between the antenna port and each of the UE’s receive antenna ports. The transmit antenna ports are also referred to as CSI-RS ports. The supported number of CSI-RS 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.

[0016] CSI-RS can be configured to be transmitted in certain REs in a slot and certain slots. Figure 3 shows an example of CSI-RS REs for 12 antenna ports, where IRE per RB per port is shown.

[0017] 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. Furthermore, a UE in NR may be configured to measure interference based on one or multiple NZP CSI-RS resource.

[0018] CSI framework in NR

[0019] 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.

[0020] Each CSI reporting setting contains at least the following information:• A CSI-RS resource setting for channel measurement• An IMR resource set for interference measurement• Optionally, a CSI-RS resource set for interference measurementTime-domain behavior, i.e., periodic, semi-persistent, or aperiodic reporting• Frequency granularity, i.e., wideband or subband• CSI parameters to be reported such as RI, 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• 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).

[0021] DFT-based precoders

[0022] A common type of precoding is to use a DFT-precoder, where the precoder vector used to precode a single-layer transmission using a single-polarized Uniform Linear Array (ULA) with N antennas is defined as:where k = 0, 1, ... ON — 1 is the precoder index and 0 is an integer oversampling factor. ukis also referred to as a one-dimension (1-D) DFT beam with beam index k. If ULA is along the horizontal dimension, each DFT beam points to an azimuth direction. If ULA is along the vertical dimension, each DFT beam points to an elevation direction. Each precoder corresponds to a DFT beam.

[0023] A corresponding precoder vector for a two-dimensional uniform planar array (UP A) antenna ports in one dimension and N2antenna ports in another dimension can be defined as specified in 3GPP TS 38.214 V17.6.0:

[0024] In the above,and 02are the over sampling factors in the two dimensions associated withand N2, respectively. vi mis also referred to as two-dimension (2-D) DFTbeam characterized by two beam indices (Z, m), one in each dimension. Each such vectorcorresponds to a 2D DFT beam.

[0025] Extending the 2-D DFT vectors for dual-polarized UPA may then be done aswhere <pn= ejnn 2is a co-phasing factor that may be selected from M-PSK alphabet such as QPK with n = 0, 1, 2, 3, and PCSI-RS isthe number of CSI-RS ports. This is the codebook for single layer CSI report with PCSI-RS ports.

[0026] A precoder matrix for multi-layer transmission may be created by appending columns of 2-D DFT vectors. An example for 2-layer precoder matrix is given as:

[0027] Such DFT-based precoders are used for instance in NR Type I CSI feedback, where each layer is associated with a 2-D DFT beam. The NR Type I CSI feedback consisting of such DFT-based precoders is defined in clause 5.2.2.2.1 of 3GPP TS 38.214.

[0028] Port splitting into antenna groups

[0029] Beamforming with large arrays can provide narrow beams which can improve the SNR. For very large arrays, however, the beams may in some cases become more narrow than desired. In “Rl-1707483, ‘Discussion on Type I CSI feedback,’ CATT, 3GPP TSG RAN WG Meeting #89, May 15th - 19th, 2017” (referred to herein as [1]), a method for splitting the ports in one dimension into two antenna groups. The motivation for this precoder design is to avoid the problem of narrow beams as the number of CSI-RS ports increases (i.e., when the array becomes larger).

[0030] In [1], the ports in the first dimension in each polarization are split into two antenna / Vi groups wherein each antenna port group in each polarization consists of — CSI-RS ports.

[0031] For the first of the two antenna groups in the first polarization, one 2-D DFT vector is selected as follows: Note that since theports in the first dimension are split into two, the index I can take ondifferent values. Thisis in contrast to the case of one 2-D DFT vector spanning allCSI-RS ports (e.g., the vl mvector described above) in which case the index I can take on N101different values.

[0032] The 2-D precoding vector for the second of the two antenna groups in the second polarization is then selected as follow: pvl',m where 6p= e 4 is an inter-antenna group co-phasing factor where p = 0, 1, 2, 3. This cophasing factor is used to adjust the phases of different antenna groups.

[0033] The 2-D precoding vector for the first of the two antenna groups is obtained by applying an inter-polarization co-phasing factor <pn.

[0034] In 3GPP TS 38.214, precoders similar to what is proposed in [1] are specified for 3 layers and 4 layers of NR Type I CSI feedback (see clause 5.2.2.2.1 of 3GPP TS 38.214) for the cases of 16 CSI-RS ports and 32 CSI-RS ports.

[0035] The 3-layer and 4-layer codebooks specified for NR Type I CSI feedback in 3GPP TS 38.214 for 16 and 32 ports are copied below:Table 1: Codebook for 3-layer CSI reporting using antenna ports 3000 to 2999+ CSI-RS (Reproduced from Table 5.2.2.2.1-7 of 3GPP TS 38.214)Table 2: Codebook for 4-layer CSI reporting using antenna ports 3000 to 2999+ CSI-RS(Reproduced from Table 5.2.2.2.1-8 of 3GPP TS 38.214)SUMMARY

[0036] Systems and methods for Precoding Matrix Indicator (PMI) generation for large arrays are provided. In some embodiments, a method performed by a User Equipment (UE) includes: determining a first 2-dimensional Discrete Fourier Transform (DFT) vector applied to a first antenna group with N ports in a first dimension and N2ports in the second dimension; determining an inter-antenna group co-phasing factor along with a second 2-dimensional DFT vector applied to a second antenna group withports in a first dimension and N2ports in the second dimension; and reporting the first 2-dimensional DFT vector, the second 2-dimentional DFT vector, and the inter-antenna group co-phasing factor to a network node as part of precoder matrix indicator feedback. In some embodiments, when the orthogonal 2-D DFT vector to be applied to a second layer (which is orthogonal to the 2-D DFT vectors applied to a first layer) is determined through offsets that are predefined in Third Generation Partnership Project (3GPP) specifications, no additional bits may be needed to indicate the orthogonal 2-DFT vector to be applied to the second layer. Hence, inter-layer interference can be reduced without additional feedback overhead.

[0037] In some embodiments, the second 2-dimensional DFT vector is orthogonal to the first 2-dimensional DFT vector. In some embodiments, the second 2-dimensional DFT vector is offset by a factor= kO1from the first 2-dimensional DFT vector in the first dimension where k is a positive integer andis an oversampling factor associated with the first dimension. In some embodiments, the second 2-dimensional DFT vector is offset by a factor m1= q02from the first 2-dimensional DFT vector in the second dimension where q is a positive integer and 02is an oversampling factor associated with the second dimension. In some embodiments, the second 2-dimensional DFT vector is offset by a factor= kO1from the first 2-dimensional DFT vector in the first dimension and by a factor m1= q02from the first 2-dimensional DFT vector in the second dimension where k and q are positive integers,is an oversampling factor associated with the first dimension, and O2is an oversampling factor associated with the second dimension.

[0038] In some embodiments, the first inter-antenna group co-phasing factor and the second inter-antenna group co-phasing factor are the same. In some embodiments, the first interantenna group co-phasing factor and the second inter-antenna group co-phasing factor are different.

[0039] In some embodiments, inter-layer interference can be reduced when employing multiple antenna groups for large arrays.

[0040] In some embodiments, when the orthogonal 2-D DFT vector to be applied to a second layer is determined through offsets that are predefined, no additional bits are needed to indicate the orthogonal 2-D DFT vector to be applied to the second layer.

[0041] In some embodiments, orthogonal 2-D precoding vectors are applied for different layers with port splitting along one of the dimensions. In some embodiments, for a second layer, a second beam orthogonal to the first beam is selected for the first antenna group in the first polarization as follows:= kO1wherein k is an integer k > 1. In some embodiments, the value of= kOTwherein k is an integer k > 1 is pre-defined in 3GPP specifications.

[0042] In some embodiments, for a second layer, an orthogonal 2-D DFT vector is selected for the first antenna group in the first polarization as follows: vLi,m+m, where m1= qO2wherein q is an integer q > 1. In some embodiments, the offset to obtain the orthogonal beam for the second layer is in the second dimension. In some embodiments, for the second layer, the 2-D DFT vector is selected for the second antenna group in the first polarization is given asInsome embodiments, the value of m1= qO2wherein q is an integer q > 1 is predefined in 3GPP specifications.

[0043] In some embodiments, the same beams are selected for the two antenna groups. In some embodiments, different beams are selected for different antenna groups. In some embodiments, there are more than two groups and where the number of groups is Ngroupfor a given type of grouping, the number of co-phase factors for that type of grouping is Ngroup— 1. In some embodiments, quantized amplitude is used for scaling for any one of the above types of co-phase factors.BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0045] Figure 1 illustrates a transmission structure of spatial multiplexing in New Radio (NR);

[0046] Figure 2 illustrates a two-dimensional antenna array of dual-polarized antenna elements (Np== 4 horizontal antenna elements and N2= 4 vertical antenna elements;

[0047] Figure 3 illustrates an example of Resource Element (RE) allocation for a 12-port Channel State Information (CSI) Reference Signals (CSI-RS) in NR;

[0048] Figure 4 illustrates an example of dividing an antenna array with 64 antenna ports (i.e., 32 cross antenna ports) into two antenna groups each with 32 ports (i.e., 16 cross polarized antenna ports);

[0049] Figure 5 illustrates an example of selecting different orthogonal beams along the first dimension for two different layers;

[0050] Figure 6 illustrates an example of selecting different orthogonal beams along the second dimension for two different layers;

[0051] Figures 7A and 7B illustrate the operation of a User Equipment device (UE);

[0052] Figures 8A and 8B illustrate the operation of a network node;

[0053] Figure 9 shows an example of a communication system in accordance with some embodiments of the present disclosure;

[0054] Figure 10 shows a UE in accordance with some embodiments of the present disclosure;

[0055] Figure 11 shows a network node in accordance with some embodiments of the present disclosure;

[0056] Figure 12 is a block diagram of a host, which may be an embodiment of the host of Figure 9, in accordance with various aspects of the present disclosure described herein;

[0057] Figure 13 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments of the present disclosure may be virtualized; and

[0058] Figure 14 shows a communication diagram of a host communicating via a network node with a UE over a partially wireless connection in accordance with some embodiments of the present disclosure.DETAILED DESCRIPTION

[0059] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0060] 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.

[0061] There currently exist certain challenge(s). Beamwidth (e.g., defined by Half-Power Beam Width (HPBW)) is inversely proportional to the number of antenna ports, assuming the spacing between adjacent antenna ports is constant. Hence, the beam width becomes narrower and narrower when the number of antenna ports increases. In some propagation conditions, the system performance may drop if the beam becomes too narrow since the system becomes much more sensitive to UE movement and it is more difficult to select a suitable beam. Furthermore, in a multipath channel, a single narrow beam may not be able to capture all energy from a scattering cluster if the beamwidth is smaller than the angular spread of the cluster. Also, when the beamwidth becomes too narrow, the system performance is more sensitive to UE channel estimation accuracy, such as the estimation of Angle of Departure (AoD). If the reported SD basis vector mismatches the DL channel, considerable DL performance drop may happen.

[0062] In NR Type I CSI feedback, when the number of antenna ports is larger than or equal to 16, for rank 3 and rank 4 CSI reporting, only half of the number of ports in one dimension is used to select a beam in that dimension (i.e., vertical or horizontal) in an attempt to mitigate the narrow beamwidth problem. This scheme is described above.

[0063] One problem with the current solution described above for 3-layer and 4-layer codebooks is that the selected 2-D precoding vectors used for one transmission layer are also used for another transmission layer in the same polarization. This may result in increased interlayer interference. For instance, for 3-layer codebook, the following 2-D precoding vectors are used over the two antenna groups in the first polarization for both the first layer and the third layers:

[0064] For 4-layer codebook, the following 2-D precoding vectors are used over the two antenna groups in the first polarization for both the first and the third layers:

[0065] For 4-layer codebook, the following 2-D precoding vectors are used over the two antenna groups in the first polarization for both the second and the fourth layers:

[0066] Hence, how to mitigate such interlayer interference is an open problem to be solved. With increasing number of ports being discussed in 3GPP (e.g., increasing number of ports to 64 ports, 96 ports, 128 ports, etc.), the above problem may become severe as the beamwidth becomes narrower. Another issue is that the solution of port splitting into antenna groups is only specified for 3-layer and 4-layer codebooks and how to realize port splitting into antenna groups while reducing the interlayer interference is also an open problem to be solved.

[0067] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. In some embodiments, a method for reducing inter-layer interference is proposed for a CSI feedback with N ports in a first dimension and N2ports in the second dimension wherein the ports along one of the first or second dimension is split into a first antenna group and a second antenna group. In some embodiments, the method includes: for a first spatial layer, determining a first 2-dimensional DFT vector applied to the first antenna group, and a first inter-antenna group co-phasing factor along with the first 2-dimensional DFT vector applied to the second antenna group; and for a second spatial layer, determining a second 2-dimensional DFT vector applied to the first antenna group, and a second inter-antenna group co-phasing factor along with the second 2-dimsional DFT vector applied to the second antenna group.

[0068] In some embodiments, the second 2-dimensional DFT vector is orthogonal to the first 2-dimensional DFT vector. In some embodiments, the second 2-dimensional DFT vector is offset by a factor= kO1from the first 2-dimensional DFT vector in the first dimension where k is a positive integer and 01is an oversampling factor associated with the first dimension.

[0069] In some embodiments, the second 2-dimensional DFT vector is offset by a factor m1= qO2from the first 2-dimensional DFT vector in the second dimension where q is a positive integer and O2is an oversampling factor associated with the second dimension.

[0070] In some embodiments, the second 2-dimensional DFT vector is offset by a factor= kO from the first 2-dimensional DFT vector in the first dimension and by a factor m1= qO2from the first 2-dimensional DFT vector in the second dimension where k and q are positive integers, 01is an oversampling factor associated with the first dimension, and O2is an oversampling factor associated with the second dimension.

[0071] In some embodiments, the first inter-antenna group co-phasing factor and the second inter-antenna group co-phasing factor are the same.

[0072] In some embodiments, the first inter-antenna group co-phasing factor and the second inter-antenna group co-phasing factor are different.

[0073] Certain embodiments may provide one or more of the following technical advantages. Furthermore, in some embodiments, when the orthogonal 2-D DFT vector to be applied to a second layer (which is orthogonal to the 2-D DFT vectors applied to a first layer) is determined through offsets that are predefined in 3GPP specifications, no additional bits may be needed to indicate the orthogonal 2-DFT vector to be applied to the second layer. Hence, inter-layer interference can be reduced without additional feedback overhead.

[0074] A large antenna array with more than 32 ports can be divided into at least two antenna groups. An example is shown in Figure 4. Each antenna group can be configured / associated to a CSI-RS resource for channel measurement. A codebook based CSI report for the large antenna array can be configured with a CSI-RS resource set with two CSI-RS resources for channel measurement wherein each antenna group corresponds to one of the two CSI-RS resources for channel measurement.

[0075] Embodiment 1 : Port splitting with Orthogonal 2-D precoding vectors across different layers (orthogonal beams along 1stdimension)

[0076] In this embodiment, orthogonal 2-D precoding vectors are applied for different layers with port splitting (dividing a large antenna array into two smaller antenna arrays or groups) along one of the dimensions (i.e., dimensions associated to either N or 1V2). Assume that the port splitting is along the first dimension (e.g., the dimension along N1). Then, for a first layer, a first beam represented by 2-D DFT vectormis selected for the first antenna group in the first polarization, and a same beam is also selected for the second antenna group in the first jyp ~ polarization with a first co-phase factor, e.g., 9p= e * (p = 0,1, 2, 3), i.e., 9pvti m. In this embodiment, for a second layer, a second beam orthogonal to the first beam is selected for the first antenna group in the first polarization as follows:^l' + 1^,171 = kO1wherein k is an integer k > 1. Then, for the second layer, the second beam is also selected for the second antenna group in the first polarization with the first co-phase factor, 9p, i.e., 9pvti+ii m. In this embodiment, the value of= kO1wherein k is an integer k > 1 is pre-defined in 3GPP specifications. This is illustrated in Figure 5, where for the second polarization, the same set of beams are used as in the first polarization while a second phase factor <pn= e]7m 2(n = 0,1) is applied on top of the same set of beams. Essentially, this means that the co-phase factor 9pis used to co-phase beams across antenna groups, while the co-phase factor <pnis used to co-phase the beams between orthogonal polarizations.

[0077] In an example of this embodiment, the codebook for 2-layers can be defined as in Table 3. In Table 3, indices i1 1and i12determine I' and m, respectively and thus determinedetermines I", thus ensuring that I" = I' +Hence, vtnmcan be written asmwhich is orthogonal to vll mgiven = kO1for an integer k > 1. Since the relationship i1+= kO1for an integer k > 1 is fixed in specifications, port splitting can be achieved with no additional bits needed to indicate the orthogonal 2-D precoding vectors across different layers. That is, the following bits are sufficient to indicate the PMI for the codebook shown in Table 3: log22bits to indicate ilas part of wideband PMI log2A / ,O2P bits to indicate t1 2as part of wideband PMI• 2 bits to indicate i13as part of wideband PMI (note that i13indicates the inter-antenna group co-phasing factor 0p)• 1 bit to indicate i2for wideband PMI or per subband PMI (note that i2indicates the interpolarization co-phasing factor <pn)

[0078] Note that for different values of k, in Table 3 can be written asfollows:•••• etc.Table 3: Codebook for 2-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 1

[0079] Note that the codebook formulation in Table 3 is a non-limiting example. The precoders in the codebook might be formulated in other ways while still preserving orthogonality between layers. For example, the precoder for the second layer may also bewhile the precoder for the first layer is the same as that in Table 3. This also applies to all the examples provided in the following sections.

[0080] Similarly, two orthogonal beams can be used for 3 and 4 layers with two antenna groups. A non-limiting example is shown in Table 4 for 3 layers and Table 5 for 4 layers.Table 4: Codebook for 3-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 1Table 5: Codebook for 4-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 1

[0081] Alternatively,= kO1may be selected by the UE and k is reported by the UE as t14e (0, 1, 2, 3).

[0082] Embodiment 2: port splitting with Orthogonal 2-D precoding vectors across different layers (orthogonal beams along 2nddimension)

[0083] In this embodiment, orthogonal 2-D precoding vectors are applied for different layers with port splitting along one of the dimensions. Assume that the port splitting is along the first dimension. Then, for a first layer, 2-D DFT vectormis selected for the first antenna group in the first polarization, and the 2-D DFT vector for the second antenna group in the first polarization is given by 9pvti m. In this embodiment, for a second layer, an orthogonal 2-D DFT vector is selected for the first antenna group in the first polarization as follows:where m1= qO2wherein q is an integer q > 1. This is different from Embodiment 1 that the offset to obtain the orthogonal beam for the second layer is in the second dimension (whereas the offset in Embodiment 1 is added in the 1stdimension). According to this embodiment, for the second layer, the 2-D DFT vector is selected for the second antenna group in the first polarization is given as 9pvt>m+m. In this embodiment, the value of m1= qO2wherein q is an integer q > 1 is pre-defined in 3GPP specifications.

[0084] This is illustrated in Figure 6, where for the second polarization, a second phase factorapplied.

[0085] In a non-limiting example of this embodiment, the codebook for 2-layers can be defined as in Table 6. In Table 6, indices i1and i12determine I' and m, respectively and thus determine It should be noted that i12+ m1determines m', thus ensuring that m' = m + m1. Hence,can be written asm+miwhich is orthogonal tomgiven m1= qO2for an integer q > 1. Since the relationship i12+ m1with m1= qO2for an integer q > 1 is fixed in specifications, port splitting can be achieved with no additional bits needed to indicate the orthogonal 2-D precoding vectors across different layers. That is, the following bits are sufficient to indicate the PMI for the codebook shown in Table 6:N O ~|• log2— bits to indicate ilas part of wideband PMI• P log2A / ,0,^1 bits to indicate i12as part of wideband PMI• 2 bits to indicate t1 3as part of wideband PMI (note that t1 3indicates the inter-antenna group co-phasing factor 9p)• 1 bit to indicate i2for wideband PMI or per subband PMI (note that i2indicates the interpolarization co-phasing factor <pn)

[0086] Note that for different values of k, in Table 6 can be written asfollows:•••• etc.Table 6: Codebook for 2-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 2

[0087] Similarly, two orthogonal beams can be used for 3 and 4 layers with two antenna groups. A non- limiting example is shown in Table 7 for 3 layers and Table 8 for 4 layersTable 7: Codebook for 3-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 2Table 8: Codebook for 4-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 2

[0088] Alternatively, m1= q02may be selected by the UE and q is reported by the UE as i1;4e (0, 1, 2, 3).

[0089] Embodiment 3: port splitting with Orthogonal 2-D precoding vectors across different layers (orthogonal beams along both 1st and 2nd dimensions)

[0090] In this embodiment, orthogonal 2-D precoding vectors are applied for different layers with port splitting along one of the dimensions. Assume that the port splitting is along the first dimension. Then, for a first layer, 2-D DFT vectormis selected for the first antenna group in the first polarization, and the 2-D DFT vector for the second antenna group in the first polarization is given by 9pvti m. In this embodiment, for a second layer, an orthogonal 2-D DFT vector is selected for the first antenna group in the first polarization as follows:= kO1and m1= qO2wherein k and q are integers satisfying k > 1 and q > 1. In one embodiment, the second beam (Z' +m + m can be one of the candidate beams:s the first selected beam. In other words, the candidate values of ( / c, q) can be (0,1), (1,1), (1,0), (2,0). The value of ( / c, q) can either be fixed in specification or selected and reported by the UE. The corresponding precoders for 2, 3, and 4 layers can be constructed similar to the examples shown from Table 2 to Table 8.

[0091] Embodiment 4: port splitting with 2-D precoding vectors across different antenna groups

[0092] In the embodiments above, same beams are selected for the two antenna groups. In alternative embodiment, different beams may be selected for different antenna groups and precoder for each layer can be a linear combination of the selected beams. For example, let ( / ', m) and ( / ", m') be the two beams selected for the 1st and the 2nd antenna groups, wherethen for 2 to 4layers the precoders can be constructed similar to the examples shown from Table 9 to Table 11. ( , q) can be predefined or reported by the UE.Table 9: Codebook for 2-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 4Table 10: Codebook for 3-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 4Table 11: Codebook for 4-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to Embodiment 4

[0093] Embodiment 5: port splitting within an antenna group

[0094] In addition to the embodiments above, there might be additional port splitting within an antenna group, where each antenna group is associated with a unique NZP CSI-RS resource. For example, consider the case where two 32-port NZP CSI-RS resources are aggregated to form a 64-port NZP CSI-RS resource, where each resource is associated with an antenna group. In this case, within each antenna group, the 32 ports might be further divided into two port groups,each with 16 ports. In this case, an additional co-phase factor, e.g., Ss= eJ7rs 4for s = 0,1, 2, 3, might be used for co-phasing between the port groups within each antenna group.

[0095] An example of Embodiment 5 is given below based on the example provided in Table 3 for Embodiment 2. In this example, there are two port groups within each antenna group.Table 12: Codebook for 2-layer CSI reporting using antenna ports 3000 to 2999+PCSI-RS according to the combination of Embodiment 5 and Embodiment 2.

[0096] Embodiment 6: generalization of co-phase factor

[0097] Note that all the above embodiments assume two groups for grouping, e.g., two antenna groups (as discussed above), or two port groups within an antenna group (discussed above). In those cases, only a single co-phase factor is needed for each type of co-phasing. In general, there might be more than two groups, e.g., 4 antenna groups or 4 port groups within an antenna group. In that case, more co-phase factors are needed for each type of grouping. Denote the number of groups as Ngroupfor a given type of grouping, the number of co-phase factors for that type of grouping is Ngroup- 1.

[0098] Also note that although the co-phase factors in the above examples are only phase, it is also possible to introduce quantized amplitude for scaling any one of the above types of cophase factors.

[0099] Figure 7 A illustrates the operation of a UE. In some embodiments, a method performed by a UE includes one or more of: with N1ports in a first dimension and N2ports in the second dimension; the ports along one of the first or second dimension is split into a first antenna group and a second antenna group; for a first spatial layer, determining (700A) a first 2- dimensional DFT vector applied to the first antenna group; determining (702A) a first interantenna group co-phasing factor along with the first 2-dimensional DFT vector applied to thesecond antenna group; for a second spatial layer, determining (704A) a second 2-dimensional DFT vector applied to the first antenna group; and determining (706A) a second inter-antenna group co-phasing factor along with the second 2-dimsional DFT vector applied to the second antenna group. Figure 7B illustrates the operation of a UE. In some embodiments, a method performed by a UE includes: determining (700B) a first 2-dimensional DFT vector applied to a first antenna group with N ports in a first dimension and N2ports in the second dimension; determining (702B) an inter-antenna group co-phasing factor along with a second 2-dimensional DFT vector applied to a second antenna group with N1ports in a first dimension and N2ports in the second dimension; reporting (704B) the first 2-dimensional DFT vector, the second 2- dimentional DFT vector, and the inter-antenna group co-phasing factor to a network node as part of precoder matrix indicator feedback.

[0100] Figure 8A illustrates the operation of a network node. In some embodiments, a method performed by a network node includes one or more of: with N1ports in a first dimension and N2ports in the second dimension; the ports along one of the first or second dimension is split into a first antenna group and a second antenna group; for a first spatial layer, determining (800A) a first 2-dimensional DFT vector applied to the first antenna group; determining (802A) a first inter-antenna group co-phasing factor along with the first 2-dimensional DFT vector applied to the second antenna group; for a second spatial layer, determining (804A) a second 2- dimensional DFT vector applied to the first antenna group; and determining (806A) a second inter-antenna group co-phasing factor along with the second 2-dimsional DFT vector applied to the second antenna group. Figure 8B illustrates the operation of a network node. In some embodiments, a method performed by a network node includes: receiving (800B) a first 2- dimensional DFT vector applied to the first antenna group, with N1ports in a first dimension and N2ports in the second dimension; and receiving (802B) an inter-antenna group co-phasing factor along with a second 2-dimensional DFT vector applied to a second antenna group with N1ports in a first dimension and N2ports in the second dimension.

[0101] Figure 9 shows an example of a communication system 900 in accordance with some embodiments.

[0102] In the example, the communication system 900 includes a telecommunication network 902 that includes an access network 904, such as a Radio Access Network (RAN), and a core network 906, which includes one or more core network nodes 908. The access network 904 includes one or more access network nodes, such as network nodes 910A and 910B (one or more of which may be generally referred to as network nodes 910), or any other similar Third Generation Partnership Project (3GPP) access nodes or non-3GPP Access Points (APs).Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 902 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 902 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 902, including one or more network nodes 910 and / or core network nodes 908.

[0103] Examples of an ORAN network node include an Open Radio Unit (O-RU), an Open Distributed Unit (O-DU), an Open Central Unit (O-CU), including an O-CU Control Plane (O- CU-CP) or an O-CU User Plane (O-CU-UP), a RAN intelligent controller (near-real time or non- real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 910 facilitate direct or indirect connection of User Equipment (UE), such as by connecting UEs 912A, 912B, 912C, and 912D (one or more of which may be generally referred to as UEs 912) to the core network 906 over one or more wireless connections.

[0104] 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 900 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 900 mayinclude and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0105] The UEs 912 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 910 and other communication devices. Similarly, the network nodes 910 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 912 and / or with other network nodes or equipment in the telecommunication network 902 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 902.

[0106] In the depicted example, the core network 906 connects the network nodes 910 to one or more hosts, such as host 916. 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 906 includes one more core network nodes (e.g., core network node 908) 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 908. 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 (SIDE), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0107] The host 916 may be under the ownership or control of a service provider other than an operator or provider of the access network 904 and / or the telecommunication network 902, and may be operated by the service provider or on behalf of the service provider. The host 916 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.

[0108] As a whole, the communication system 900 of Figure 9 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 900 may be configured to operate according to predefined rules or procedures, such as specific standards thatinclude, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable Second, Third, Fourth, or Fifth Generation (2G, 3G, 4G, or 5G) standards, or any applicable future generation standard (e.g., Sixth Generation (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.

[0109] In some examples, the telecommunication network 902 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunication network 902 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 902. For example, the telecommunication network 902 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 Internet of Things (loT) services to yet further UEs.

[0110] In some examples, the UEs 912 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 904 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 904. Additionally, a UE may be configured for operating in single- or multi-Radio Access Technology (RAT) or multi-standard mode. For example, a UE may operate with any one or combination of WiFi, New Radio (NR), and LTE, i.e., being configured for Multi-Radio Dual Connectivity (MR-DC), such as Evolved UMTS Terrestrial RAN (E-UTRAN) NR - Dual Connectivity (EN-DC).

[0111] In the example, a hub 914 communicates with the access network 904 to facilitate indirect communication between one or more UEs (e.g., UE 912C and / or 912D) and network nodes (e.g., network node 910B). In some examples, the hub 914 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 914 may be a broadband router enabling access to the core network 906 for the UEs. As another example, the hub 914 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 910, or by executable code, script, process, or other instructions in the hub 914. As another example, the hub 914 may be a data collector that acts astemporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 914 may be a content source. For example, for a UE that is a Virtual Reality (VR) headset, display, loudspeaker or other media delivery device, the hub 914 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 914 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 914 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0112] The hub 914 may have a constant / persistent or intermittent connection to the network node 91 OB. The hub 914 may also allow for a different communication scheme and / or schedule between the hub 914 and UEs (e.g., UE 912C and / or 912D), and between the hub 914 and the core network 906. In other examples, the hub 914 is connected to the core network 906 and / or one or more UEs via a wired connection. Moreover, the hub 914 may be configured to connect to a Machine-to-Machine (M2M) service provider over the access network 904 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 910 while still connected via the hub 914 via a wired or wireless connection. In some embodiments, the hub 914 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 910B. In other embodiments, the hub 914 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and the network node 910B, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0113] Figure 10 shows a UE 1000 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 Internet Protocol (VoIP) phone, wireless local loop phone, desktop computer, Personal Digital Assistant (PDA), wireless camera, 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, vehiclemounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3GPP, including a Narrowband Internet of Things (NB-IoT) UE, a Machine Type Communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0114] A UE may support Device-to-Device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), or Vehicle-to-E very thing (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).

[0115] The UE 1000 includes processing circuitry 1002 that is operatively coupled via a bus 1004 to an input / output interface 1006, a power source 1008, memory 1010, a communication interface 1012, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 10. 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.

[0116] The processing circuitry 1002 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 1010. The processing circuitry 1002 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 1002 may include multiple Central Processing Units (CPUs).

[0117] In the example, the input / output interface 1006 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 1000. 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. Thepresence-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.

[0118] In some embodiments, the power source 1008 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 1008 may further include power circuitry for delivering power from the power source 1008 itself, and / or an external power source, to the various parts of the UE 1000 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1008. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1008 to make the power suitable for the respective components of the UE 1000 to which power is supplied.

[0119] The memory 1010 may be or be configured to include memory such as Random Access Memory (RAM), Read Only Memory (ROM), Programmable ROM (PROM), Erasable PROM (EPROM), Electrically EPROM (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1010 includes one or more application programs 1014, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1016. The memory 1010 may store, for use by the UE 1000, any of a variety of various operating systems or combinations of operating systems.

[0120] The memory 1010 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 RAM (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a tamper resistant module in the form of a Universal Integrated Circuit Card (UICC) including one or more Subscriber Identity Modules (SIMs), such as a Universal SIM (USIM) and / or Internet Protocol Multimedia Services Identity Module (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 a ‘SIM card.’ The memory1010 may allow the UE 1000 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 1010, which may be or comprise a device-readable storage medium.

[0121] The processing circuitry 1002 may be configured to communicate with an access network or other network using the communication interface 1012. The communication interface 1012 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1022. The communication interface 1012 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 1018 and / or a receiver 1020 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1018 and receiver 1020 may be coupled to one or more antennas (e.g., the antenna 1022) and may share circuit components, software, or firmware, or alternatively be implemented separately.

[0122] In the illustrated embodiment, communication functions of the communication interface 1012 may include cellular communication, WiFi communication, LPWAN communication, data communication, voice communication, multimedia communication, short- range communications such as Bluetooth, NFC, 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 according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband CDMA (WCDMA), GSM, LTE, NR, UMTS, WiMax, Ethernet, Transmission Control Protocol / Internet Protocol (TCP / IP), Synchronous Optical Networking (SONET), Asynchronous Transfer Mode (ATM), Quick User Datagram Protocol Internet Connection (QUIC), Hypertext Transfer Protocol (HTTP), and so forth.

[0123] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1012, 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).

[0124] 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.

[0125] A UE, when in the form of an 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 television, 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 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 1000 shown in Figure 10.

[0126] 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 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship, an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0127] 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 mayadjust 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.

[0128] Figure 11 shows a network node 1100 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, APs (e.g., radio APs), Base Stations (BSs) (e.g., radio BSs, Node Bs, evolved Node Bs (eNBs), NR Node Bs (gNBs)), and O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O- CU).

[0129] 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, distributed units (e.g., in an O-RAN access node), and / or Remote Radio Units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such RRUs 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).

[0130] 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 BS 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).

[0131] The network node 1100 includes processing circuitry 1102, memory 1104, a communication interface 1106, and a power source 1108. The network node 1100 may be composed of multiple physically separate components (e.g., a NodeB component and an 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 1100 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate componentsmay 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 1100 may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate memory 1104 for different RATs) and some components may be reused (e.g., a same antenna 1110 may be shared by different RATs). The network node 1100 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1100, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, Long Range Wide Area Network (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 the network node 1100.

[0132] The processing circuitry 1102 may comprise a combination of one or more of a microprocessor, controller, microcontroller, CPU, DSP, ASIC, FPGA, 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 1100 components, such as the memory 1104, to provide network node 1100 functionality.

[0133] In some embodiments, the processing circuitry 1102 includes a System on a Chip (SOC). In some embodiments, the processing circuitry 1102 includes one or more of Radio Frequency (RF) transceiver circuitry 1112 and baseband processing circuitry 1114. In some embodiments, the RF transceiver circuitry 1112 and the baseband processing circuitry 1114 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 the RF transceiver circuitry 1112 and the baseband processing circuitry 1114 may be on the same chip or set of chips, boards, or units.

[0134] The memory 1104 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, RAM, 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 1102. The memory 1104 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 1102 and utilized by the network node 1100. The memory 1104 may be used to store any calculations made by the processing circuitry 1102and / or any data received via the communication interface 1106. In some embodiments, the processing circuitry 1102 and the memory 1104 are integrated.

[0135] The communication interface 1106 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 1106 comprises port(s) / terminal(s) 1116 to send and receive data, for example to and from a network over a wired connection. The communication interface 1106 also includes radio front-end circuitry 1118 that may be coupled to, or in certain embodiments a part of, the antenna 1110. The radio front-end circuitry 1118 comprises filters 1120 and amplifiers 1122. The radio front-end circuitry 1118 may be connected to the antenna 1110 and the processing circuitry 1102. The radio front-end circuitry 1118 may be configured to condition signals communicated between the antenna 1110 and the processing circuitry 1102. The radio front-end circuitry 1118 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 1118 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of the filters 1120 and / or the amplifiers 1122. The radio signal may then be transmitted via the antenna 1110. Similarly, when receiving data, the antenna 1110 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1118. The digital data may be passed to the processing circuitry 1102. In other embodiments, the communication interface 1106 may comprise different components and / or different combinations of components.

[0136] In certain alternative embodiments, the network node 1100 does not include separate radio front-end circuitry 1118; instead, the processing circuitry 1102 includes radio front-end circuitry and is connected to the antenna 1110. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1112 is part of the communication interface 1106. In still other embodiments, the communication interface 1106 includes the one or more ports or terminals 1116, the radio front-end circuitry 1118, and the RF transceiver circuitry 1112 as part of a radio unit (not shown), and the communication interface 1106 communicates with the baseband processing circuitry 1114, which is part of a digital unit (not shown).

[0137] The antenna 1110 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1110 may be coupled to the radio front-end circuitry 1118 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1110 is separate from the network node 1100 and connectable to the network node 1100 through an interface or port.

[0138] The antenna 1110, the communication interface 1106, and / or the processing circuitry 1102 may be configured to perform any receiving operations and / or certain obtaining operationsdescribed herein as being performed by the network node 1100. Any information, data, and / or signals may be received from a UE, another network node, and / or any other network equipment. Similarly, the antenna 1110, the communication interface 1106, and / or the processing circuitry 1102 may be configured to perform any transmitting operations described herein as being performed by the network node 1100. Any information, data, and / or signals may be transmitted to a UE, another network node, and / or any other network equipment.

[0139] The power source 1108 provides power to the various components of the network node 1100 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1108 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1100 with power for performing the functionality described herein. For example, the network node 1100 may be connectable to an external power source (e.g., the power grid or an electricity outlet) via input circuitry or an interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1108. As a further example, the power source 1108 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.

[0140] Embodiments of the network node 1100 may include additional components beyond those shown in Figure 11 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 1100 may include user interface equipment to allow input of information into the network node 1100 and to allow output of information from the network node 1100. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1100.

[0141] Figure 12 is a block diagram of a host 1200, which may be an embodiment of the host 916 of Figure 9, in accordance with various aspects described herein. As used herein, the host 1200 may be or comprise various combinations of 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 1200 may provide one or more services to one or more UEs.

[0142] The host 1200 includes processing circuitry 1202 that is operatively coupled via a bus 1204 to an input / output interface 1206, a network interface 1208, a power source 1210, and memory 1212. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices ofprevious figures, such as Figures 10 and 11, such that the descriptions thereof are generally applicable to the corresponding components of the host 1200.

[0143] The memory 1212 may include one or more computer programs including one or more host application programs 1214 and data 1216, which may include user data, e.g., data generated by a UE for the host 1200 or data generated by the host 1200 for a UE. Embodiments of the host 1200 may utilize only a subset or all of the components shown. The host application programs 1214 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), Moving Picture Experts Group (MPEG), VP9) and audio codecs (e.g., Free Lossless Audio Codec (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, and heads-up display systems). The host application programs 1214 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 1200 may select and / or indicate a different host for Over-The-Top (OTT) services for a UE. The host application programs 1214 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (DASH or MPEG-DASH), etc.

[0144] Figure 13 is a block diagram illustrating a virtualization environment 1300 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 1300 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. In some embodiments, the virtualization environment 1300 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0145] Applications 1302 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1300 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0146] Hardware 1304 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 1306 (also referred to as hypervisors or VM Monitors (VMMs)), provide VMs 1308 A and 1308B (one or more of which may be generally referred to as VMs 1308), and / or perform any of the functions, features, and / or benefits described in relation with some embodiments described herein. The virtualization layer 1306 may present a virtual operating platform that appears like networking hardware to the VMs 1308.

[0147] The VMs 1308 comprise virtual processing, virtual memory, virtual networking, or interface and virtual storage, and may be run by a corresponding virtualization layer 1306. Different embodiments of the instance of a virtual appliance 1302 may be implemented on one or more of the VMs 1308, 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.

[0148] In the context of NFV, a VM 1308 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 1308, and that part of the hardware 1304 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs 1308, 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 1308 on top of the hardware 1304 and corresponds to the application 1302.

[0149] The hardware 1304 may be implemented in a standalone network node with generic or specific components. The hardware 1304 may implement some functions via virtualization. Alternatively, the hardware 1304 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 1310, which, among others, oversees lifecycle management of the applications 1302. In some embodiments, the hardware 1304 is coupled to one or more radiounits 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 RAN or a base station. In some embodiments, some signaling can be provided with the use of a control system 1312 which may alternatively be used for communication between hardware nodes and radio units.

[0150] Figure 14 shows a communication diagram of a host 1402 communicating via a network node 1404 with a UE 1406 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as the UE 912A of Figure 9 and / or the UE 1000 of Figure 10), the network node (such as the network node 910A of Figure 9 and / or the network node 1100 of Figure 11), and the host (such as the host 916 of Figure 9 and / or the host 1200 of Figure 12) discussed in the preceding paragraphs will now be described with reference to Figure 14.

[0151] Like the host 1200, embodiments of the host 1402 include hardware, such as a communication interface, processing circuitry, and memory. The host 1402 also includes software, which is stored in or is accessible by the host 1402 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 1406 connecting via an OTT connection 1450 extending between the UE 1406 and the host 1402. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 1450.

[0152] The network node 1404 includes hardware enabling it to communicate with the host 1402 and the UE 1406. The connection 1460 may be direct or pass through a core network (like the core network 906 of Figure 9) 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.

[0153] The UE 1406 includes hardware and software, which is stored in or accessible by the UE 1406 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 the UE 1406 with the support of the host 1402. In the host 1402, an executing host application may communicate with the executing client application via the OTT connection 1450 terminating at the UE 1406 and the host 1402. 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 1450 may transfer both the request data and the user data. The UE’s client application may interact with theuser to generate the user data that it provides to the host application through the OTT connection 1450.

[0154] The OTT connection 1450 may extend via the connection 1460 between the host 1402 and the network node 1404 and via a wireless connection 1470 between the network node 1404 and the UE 1406 to provide the connection between the host 1402 and the UE 1406. The connection 1460 and the wireless connection 1470, over which the OTT connection 1450 may be provided, have been drawn abstractly to illustrate the communication between the host 1402 and the UE 1406 via the network node 1404, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

[0155] As an example of transmitting data via the OTT connection 1450, in step 1408, the host 1402 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 1406. In other embodiments, the user data is associated with a UE 1406 that shares data with the host 1402 without explicit human interaction. In step 1410, the host 1402 initiates a transmission carrying the user data towards the UE 1406. The host 1402 may initiate the transmission responsive to a request transmitted by the UE 1406. The request may be caused by human interaction with the UE 1406 or by operation of the client application executing on the UE 1406. The transmission may pass via the network node 1404 in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 1412, the network node 1404 transmits to the UE 1406 the user data that was carried in the transmission that the host 1402 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1414, the UE 1406 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 1406 associated with the host application executed by the host 1402.

[0156] In some examples, the UE 1406 executes a client application which provides user data to the host 1402. The user data may be provided in reaction or response to the data received from the host 1402. Accordingly, in step 1416, the UE 1406 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 1406. Regardless of the specific manner in which the user data was provided, the UE 1406 initiates, in step 1418, transmission of the user data towards the host 1402 via the network node 1404. In step 1420, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 1404 receives user data from the UE 1406 and31 initiates transmission of the received user data towards the host 1402. In step 1422, the host 1402 receives the user data carried in the transmission initiated by the UE 1406.

[0157] One or more of the various embodiments improve the performance of OTT services provided to the UE 1406 using the OTT connection 1450, in which the wireless connection 1470 forms the last segment. More precisely, the teachings of these embodiments may improve the e.g., data rate, latency, power consumption, etc. and thereby provide benefits such as e.g., reduced user waiting time, relaxed restriction on file size, improved content resolution, better responsiveness, extended battery lifetime, etc.

[0158] In an example scenario, factory status information may be collected and analyzed by the host 1402. As another example, the host 1402 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 1402 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 1402 may store surveillance video uploaded by a UE. As another example, the host 1402 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 1402 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.

[0159] 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 1450 between the host 1402 and the UE 1406 in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection 1450 may be implemented in software and hardware of the host 1402 and / or the UE 1406. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 1450 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or by supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 1450 may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not directly alter the operation of the network node 1404. 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 bythe host 1402. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 1450 while monitoring propagation times, errors, etc.

[0160] 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.

[0161] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored 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 hardwired 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.

[0162] EMBODIMENTS

[0163] Group A Embodiments

[0164] Embodiment 1 : A method performed by a user equipment, the method comprising one or more of:ports in a first dimension and N2ports in the second dimension; the ports along one of the first or second dimension is split into a first antenna group and a second antenna group; for a first spatial layer, determining (700) a first 2-dimensional Discrete Fourier Transform, DFT, vector applied to the first antenna group; determining (702) a first inter-antenna group co-phasing factor along with the first 2-dimensional DFT vector applied to the second antenna group; for a second spatial layer, determining (704) a second 2-dimensional DFT vector applied to the first antenna group; and determining (706) a second inter-antenna group cophasing factor along with the second 2-dimsional DFT vector applied to the second antenna group.

[0165] Embodiment 2: The method of the previous embodiment, wherein the second 2- dimensional DFT vector is orthogonal to the first 2-dimensional DFT vector.

[0166] Embodiment 3: The method of any of the previous embodiments, wherein the second 2-dimensional DFT vector is offset by a factor= kO1from the first 2-dimensional DFT vector in the first dimension where k is a positive integer and 01is an oversampling factor associated with the first dimension.

[0167] Embodiment 4: The method of any of the previous embodiments, wherein the second 2-dimensional DFT vector is offset by a factor m1= qO2from the first 2-dimensional DFT vector in the second dimension where q is a positive integer and O2is an oversampling factor associated with the second dimension.

[0168] Embodiment 5: The method of any of the previous embodiments, wherein the second 2-dimensional DFT vector is offset by a factor= kO from the first 2-dimensional DFT vector in the first dimension and by a factor m1= qO2from the first 2-dimensional DFT vector in the second dimension where k and q are positive integers, 01is an oversampling factor associated with the first dimension, and O2is an oversampling factor associated with the second dimension.

[0169] Embodiment 6: The method of any of the previous embodiments, wherein the first inter-antenna group co-phasing factor and the second inter-antenna group co-phasing factor are the same.

[0170] Embodiment 7: The method of any of the previous embodiments, wherein the first inter-antenna group co-phasing factor and the second inter-antenna group co-phasing factor are different.

[0171] Embodiment 8: The method of any of the previous embodiments, wherein interlayer interference can be reduced when employing multiple antenna groups for large arrays.

[0172] Embodiment 9: The method of any of the previous embodiments, wherein, when the orthogonal 2-D DFT vector to be applied to a second layer is determined through offsets that are predefined, no additional bits are needed to indicate the orthogonal 2-D DFT vector to be applied to the second layer.

[0173] Embodiment 10: The method of any of the previous embodiments, wherein orthogonal 2-D precoding vectors are applied for different layers with port splitting (e.g., dividing a large antenna array into two smaller antenna arrays or groups) along one of the dimensions (e.g., dimensions associated to either N or 1V2).

[0174] Embodiment 11 : The method of any of the previous embodiments, wherein for a second layer, a second beam orthogonal to the first beam is selected for the first antenna group in the first polarization as follows:= kO1wherein k is an integer k > 1.

[0175] Embodiment 12: The method of any of the previous embodiments, wherein the value = kO1wherein k is an integer k > 1 is pre-defined in 3GPP specifications.

[0176] Embodiment 13: The method of any of the previous embodiments, wherein for a second layer, an orthogonal 2-D DFT vector is selected for the first antenna group in the first polarization as follows: Vp ^m+m, where m1= q02wherein q is an integer q > 2.

[0177] Embodiment 14: The method of any of the previous embodiments, wherein the offset to obtain the orthogonal beam for the second layer is in the second dimension.

[0178] Embodiment 15: The method of any of the previous embodiments, wherein for the second layer, the 2-D DFT vector is selected for the second antenna group in the first polarization is given as 9pVii>m+m.

[0179] Embodiment 16: The method of any of the previous embodiments, wherein the value of m1= q02wherein q is an integer q > 1 is pre-defined in 3GPP specifications.

[0180] Embodiment 17: The method of any of the previous embodiments, wherein the same beams are selected for the two antenna groups.

[0181] Embodiment 18: The method of any of the previous embodiments, wherein different beams are selected for different antenna groups.

[0182] Embodiment 19: The method of any of the previous embodiments, wherein there are more than two groups, (e.g., 4 antenna groups or 4 port groups within an antenna group) and, where the number of groups is Ngroupfor a given type of grouping, the number of co-phase factors for that type of grouping is Ngroup— 2.

[0183] Embodiment 20: The method of any of the previous embodiments, wherein quantized amplitude is used for scaling for any one of the above types of co-phase factors.

[0184] Embodiment 21 : The method of any of the previous embodiments, further comprising: providing user data; and forwarding the user data to a host via the transmission to the network node.

[0185] Group B Embodiments

[0186] Embodiment 22: A method performed by a network node, the method comprising one or more of: with N ports in a first dimension and N2ports in the second dimension; the ports along one of the first or second dimension is split into a first antenna group and a second antenna group; for a first spatial layer, determining (800) a first 2-dimensional DFT vector applied to the first antenna group; determining (802) a first inter-antenna group co-phasing factor along with the first 2-dimensional DFT vector applied to the second antenna group; for a second spatial layer, determining (804) a second 2-dimensional DFT vector applied to the first antenna group; and determining (806) a second inter-antenna group co-phasing factor along with the second 2-dimsional DFT vector applied to the second antenna group.

[0187] Embodiment 23: The method of the previous embodiment, wherein the second 2- dimensional DFT vector is orthogonal to the first 2-dimensional DFT vector.

[0188] Embodiment 24: The method of any of the previous embodiments, wherein the second 2-dimensional DFT vector is offset by a factor= kO1from the first 2-dimensional DFT vector in the first dimension where k is a positive integer andis an oversampling factor associated with the first dimension.

[0189] Embodiment 25: The method of any of the previous embodiments, wherein the second 2-dimensional DFT vector is offset by a factor m1= qO2from the first 2-dimensional DFT vector in the second dimension where q is a positive integer and O2is an oversampling factor associated with the second dimension.

[0190] Embodiment 26: The method of any of the previous embodiments, wherein the second 2-dimensional DFT vector is offset by a factor = kO1from the first 2-dimensional DFT vector in the first dimension and by a factor m1= qO2from the first 2-dimensional DFT vector in the second dimension where k and q are positive integers,is an oversampling factor associated with the first dimension, and O2is an oversampling factor associated with the second dimension.

[0191] Embodiment 27: The method of any of the previous embodiments, wherein the first inter-antenna group co-phasing factor and the second inter-antenna group co-phasing factor are the same.

[0192] Embodiment 28: The method of any of the previous embodiments, wherein the first inter-antenna group co-phasing factor and the second inter-antenna group co-phasing factor are different.

[0193] Embodiment 29: The method of any of the previous embodiments, wherein interlayer interference can be reduced when employing multiple antenna groups for large arrays.

[0194] Embodiment 30: The method of any of the previous embodiments, wherein, when the orthogonal 2-D DFT vector to be applied to a second layer is determined through offsets that are predefined, no additional bits are needed to indicate the orthogonal 2-D DFT vector to be applied to the second layer.

[0195] Embodiment 31 : The method of any of the previous embodiments, wherein orthogonal 2-D precoding vectors are applied for different layers with port splitting (e.g., dividing a large antenna array into two smaller antenna arrays or groups) along one of the dimensions (e.g., dimensions associated to eitheror 1V2).

[0196] Embodiment 32: The method of any of the previous embodiments, wherein for a second layer, a second beam orthogonal to the first beam is selected for the first antenna group in the first polarization as follows: vp+j= kO1wherein k is an integer k > 1.

[0197] Embodiment 33: The method of any of the previous embodiments, wherein the value = kO1wherein k is an integer k > 1 is pre-defined in 3GPP specifications.

[0198] Embodiment 34: The method of any of the previous embodiments, wherein for a second layer, an orthogonal 2-D DFT vector is selected for the first antenna group in the first polarization as follows: Vp ^m+m, where m1= q02wherein q is an integer q > 1.

[0199] Embodiment 35: The method of any of the previous embodiments, wherein the offset to obtain the orthogonal beam for the second layer is in the second dimension.

[0200] Embodiment 36: The method of any of the previous embodiments, wherein for the second layer, the 2-D DFT vector is selected for the second antenna group in the first polarization is given as 0pVt>m+m.

[0201] Embodiment 37: The method of any of the previous embodiments, wherein the value of m1= q02wherein q is an integer q > 1 is pre-defined in 3GPP specifications.

[0202] Embodiment 38: The method of any of the previous embodiments, wherein the same beams are selected for the two antenna groups.

[0203] Embodiment 39: The method of any of the previous embodiments, wherein different beams are selected for different antenna groups.

[0204] Embodiment 40: The method of any of the previous embodiments, wherein there are more than two groups, (e.g., 4 antenna groups or 4 port groups within an antenna group) and,where the number of groups is Ngroupfor a given type of grouping, the number of co-phase factors for that type of grouping is Ngroup— 1.

[0205] Embodiment 41 : The method of any of the previous embodiments, wherein quantized amplitude is used for scaling for any one of the above types of co-phase factors.

[0206] Embodiment 42: 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.

[0207] Group C Embodiments

[0208] Embodiment 43: A user equipment, comprising: processing circuitry configured to perform any of the steps of any of the Group A embodiments; and power supply circuitry configured to supply power to the processing circuitry.

[0209] Embodiment 44: A network node, the network node comprising: processing circuitry configured to perform any of the steps of any of the Group B embodiments; and power supply circuitry configured to supply power to the processing circuitry.

[0210] Embodiment 45: A user equipment (UE), 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 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.

[0211] Embodiment 46: 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 user equipment (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 embodiments to transmit the user data from the host to the UE.

[0212] Embodiment 47 : The host of the previous 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.

[0213] Embodiment 48: A method implemented in a host configured to operate in a communication system that further includes a network node and a user equipment (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 embodiments to transmit the user data from the host to the UE.

[0214] Embodiment 49: The method of the previous embodiment, further comprising, at the network node, transmitting the user data provided by the host for the UE.

[0215] Embodiment 50: The method of any of the previous 2 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.

[0216] Embodiment 51: A communication system configured to provide an over-the-top (OTT) 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 embodiments to transmit the user data from the host to the UE.

[0217] Embodiment 52: The communication system of the previous embodiment, further comprising: the network node; and / or the UE.

[0218] Embodiment 53: A host configured to operate in a communication system to provide an over-the-top (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 embodiments to receive the user data from a user equipment (UE) for the host.

[0219] Embodiment 54: The host of the previous 2 embodiments, wherein: the processing circuitry of the host is configured to execute a host application that receives 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.

[0220] Embodiment 55: The host of the any of the previous 2 embodiments, wherein the initiating receipt of the user data comprises requesting the user data.

[0221] Embodiment 56: 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, 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 embodiments to receive the user data from the UE for the host.

[0222] Embodiment 57 : The method of the previous embodiment, further comprising at the network node, transmitting the received user data to the host.

[0223] Embodiment 58: 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 operations of any of the Group A embodiments to receive the user data from the host.

[0224] Embodiment 59: The host of the previous 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.

[0225] Embodiment 60: The host of the previous 2 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.

[0226] Embodiment 61 : A method implemented by a host operating in a communication system that further includes a network node and a user equipment (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.

[0227] Embodiment 62: The method of the previous 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 host application.

[0228] Embodiment 63: The method of the previous 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.

[0229] Embodiment 64: 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 embodiments to transmit the user data to the host.

[0230] Embodiment 65: The host of the previous 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.

[0231] Embodiment 66: The host of the previous 2 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.

[0232] Embodiment 67 : 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 embodiments to transmit the user data to the host.

[0233] Embodiment 68: The method of the previous 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.

[0234] Embodiment 69: The method of the previous 2 embodiments, 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.

[0235] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.ABBREVIATIONSAt least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).Ix RTT CDMA2000 lx Radio Transmission Technology 3GPP 3rd Generation Partnership Project 5G 5th Generation 6G 6th Generation ABS Almost Blank Subframe ARQ Automatic Repeat Request AWGN Additive White Gaussian Noise BCCH Broadcast Control Channel BCH Broadcast Channel CA Carrier Aggregation CC Carrier Component CCCH SDU Common Control Channel SDU CDMA Code Division Multiplexing Access CGI Cell Global Identifier CIR Channel Impulse Response CP Cyclic Prefix CPICH Common Pilot Channel CPICH Ec / No CPICH Received energy per chip divided by the power density in the band CQI Channel Quality information C-RNTI Cell RNTI CSI Channel State Information DCCH Dedicated Control Channel DFT Discrete Fourier Transform DL Downlink DM Demodulation DMRS Demodulation Reference Signal DRX Discontinuous Reception DTX Discontinuous Transmission DTCH Dedicated Traffic Channel DUT Device Under Test E-CID Enhanced Cell- ID (positioning method) eMBMS evolved Multimedia Broadcast Multicast Services E-SMLC Evolved-Serving Mobile Location Centre ECGI Evolved CGI eNB E-UTRAN NodeB ePDCCH Enhanced Physical Downlink Control Channel E-SMLC Evolved Serving Mobile Location Center E-UTRA Evolved UTRA E-UTRAN Evolved UTRAN FDD Frequency Division Duplex FFS For Further Study gNB Base station in NR GNSS Global Navigation Satellite System HARQ Hybrid Automatic Repeat RequestHO HandoverHSPA High Speed Packet AccessHRPD High Rate Packet DataLOS Line of SightLPP LTE Positioning ProtocolLTE Long-Term EvolutionMAC Medium Access ControlMAC Message Authentication CodeMBSFN Multimedia Broadcast multicast service Single Frequency NetworkMBSFN ABS MBSFN Almost Blank SubframeMDT Minimization of Drive TestsMIB Master Information BlockMME Mobility Management EntityMSC Mobile Switching CenterNPDCCH Narrowband Physical Downlink Control ChannelNR New RadioNZP Non-Zero PowerOCNG OFDMA Channel Noise GeneratorOFDM Orthogonal Frequency Division MultiplexingOFDMA Orthogonal Frequency Division Multiple AccessOSS Operations Support SystemOTDOA Observed Time Difference of ArrivalO&M Operation and MaintenancePBCH Physical Broadcast ChannelP-CCPCH Primary Common Control Physical ChannelPCell Primary CellPCFICH Physical Control Format Indicator ChannelPDCCH Physical Downlink Control ChannelPDCP Packet Data Convergence ProtocolPDP Profile Delay ProfilePDSCH Physical Downlink Shared ChannelPGW Packet GatewayPHICH Physical Hybrid-ARQ Indicator ChannelPLMN Public Land Mobile NetworkPMI Precoder Matrix IndicatorPRACH Physical Random Access ChannelPRS Positioning Reference SignalPSS Primary Synchronization SignalPUCCH Physical Uplink Control ChannelPUSCH Physical Uplink Shared ChannelRACH Random Access ChannelQAM Quadrature Amplitude ModulationRAN Radio Access NetworkRAT Radio Access TechnologyRLC Radio Link ControlRLM Radio Link ManagementRNC Radio Network ControllerRNTI Radio Network Temporary IdentifierRRC Radio Resource ControlRRM Radio Resource ManagementRS Reference SignalRSCP Received Signal Code PowerRSRP Reference Symbol Received Power OR Reference Signal Received PowerRSRQ Reference Signal Received Quality OR Reference Symbol Received QualityRSSI Received Signal Strength IndicatorRSTD Reference Signal Time DifferenceSCH Synchronization ChannelSCell Secondary CellSDAP Service Data Adaptation ProtocolSDU Service Data UnitSFN System Frame NumberSGW Serving GatewaySI System InformationSIB System Information BlockSNR Signal to Noise RatioSON Self Optimized NetworkSS Synchronization SignalSSS Secondary Synchronization SignalTDD Time Division DuplexTDOA Time Difference of ArrivalTOA Time of ArrivalTSS Tertiary Synchronization SignalTTI Transmission Time IntervalUE User EquipmentUL UplinkUSIM Universal Subscriber Identity ModuleUTDOA Uplink Time Difference of ArrivalWCDMA Wide CDMAWLAN Wide Local Area Network

Claims

CLAIMS1. A method performed by a User Equipment, UE, the method comprising: determining (700B) a first 2-dimensional Discrete Fourier Transform, DFT, vector applied to a first antenna group with N ports in a first dimension and N2ports in the second dimension; determining (702B) an inter-antenna group co-phasing factor along with a second 2- dimensional DFT vector applied to a second antenna group withports in a first dimension and N2ports in the second dimension; and reporting (704B) the first 2-dimensional DFT vector, the second 2-dimentional DFT vector, and the inter-antenna group co-phasing factor to a network node as part of precoder matrix indicator feedback.

2. The method of claim 1, wherein the first antenna group and the second antenna group are associated with a first NZP CSLRS resource and a second NZP CSI-RS resource, respectively.

3. The method of any of claims 1 and 2, wherein the second 2-dimensional DFT vector is orthogonal to the first 2-dimensional DFT vector.

4. The method of any of claims 1-3, wherein the second 2-dimensional DFT vector is offset by a factor= kO1from the first 2-dimensional DFT vector in the first dimension where k is a positive integer andis an oversampling factor associated with the first dimension.

5. The method of any of claims 1-3, wherein the second 2-dimensional DFT vector is offset by a factor m1= q02from the first 2-dimensional DFT vector in the second dimension where q is a positive integer and 02is an oversampling factor associated with the second dimension.

6. The method of any of claims 1-3, wherein the second 2-dimensional DFT vector is offset by a factor= kO1from the first 2-dimensional DFT vector in the first dimension and by a factor m1= q02from the first 2-dimensional DFT vector in the second dimension where k and q are positive integers,is an oversampling factor associated with the first dimension, and 02is an oversampling factor associated with the second dimension.

7. The method of any of claims 1-6, wherein orthogonal 2-D precoding vectors are applied for different layers with port splitting along one of the dimensions.

8. The method of any of claims 1-7, wherein the second 2-dimensional DFT vector orthogonal to the first 2-dimensional DFT vector,is determined as follows:m, where wherein k is an integer k > 1.

9. The method of claim 8, wherein the value of= kO1wherein k is an integer k > 1 predefined in 3GPP specifications.

10. The method of any of claims 8-9, wherein the 2-D precoding vector applied to the second antenna group is given as 0pv( / +(i mwhere 9pis the inter-antenna group co-phasing factor.

11. The method of any of claims 1-7, wherein the second 2-dimensional DFT vector orthogonal to the first 2-dimentional DFT vector,is determined as follows: vLi^m+m, where m1= q02wherein q is an integer q > 1.

12. The method of claim 11, wherein the value of m1= q02wherein q is an integer q > 1 pre-defined in 3GPP specifications.

13. The method of any of claims 11-12, wherein the 2-D precoding vector applied to the second antenna group is given as 9pvt>m+mwhere 9pis the inter-antenna group co-phasing factor.

14. The method of any of claims 1-7, wherein the second 2-dimensional DFT vector orthogonal to the first 2-dimentional DFT vector,is determined as follows:,m+m,wherein k and q are integers k > 1, q > 1.

15. The method of claim 14, wherein the values of= kO1and m1= q02wherein k and q are integers k > 1, q > 1 pre-defined in 3GPP specifications.

16. The method of any of claims 14-15, wherein the 2-D precoding vector applied to the second antenna group is given as 0pvp+j where 9pis the inter-antenna group co-phasingfactor.

17. The method of any of claims 1-16, wherein there are more than two antenna groups and where the number of antenna groups is Ngroupfor a given type of grouping, the number of interantenna group co-phase factors for that type of grouping is Ngroup— 1.

18. A method performed by a network node, the method comprising: receiving (800B) a first 2-dimensional Discrete Fourier Transform, DFT, vector applied to the first antenna group, with N1ports in a first dimension and N2ports in the second dimension; and receiving (802B) an inter-antenna group co-phasing factor along with a second 2- dimensional DFT vector applied to a second antenna group with N1ports in a first dimension and N2ports in the second dimension.

19. The method of claim 18, wherein the first antenna group and the second antenna group are associated with a first NZP CSI-RS resource and a second NZP CSI-RS resource, respectively.

20. The method of claim 18, wherein the second 2-dimensional DFT vector is orthogonal to the first 2-dimensional DFT vector.

21. The method of claim 18, wherein the second 2-dimensional DFT vector is offset by a factor = kO from the first 2-dimensional DFT vector in the first dimension where k is a positive integer and 01is an oversampling factor associated with the first dimension.

22. The method of claim 18, wherein the second 2-dimensional DFT vector is offset by a factor m1= q02from the first 2-dimensional DFT vector in the second dimension where q is a positive integer and 02is an oversampling factor associated with the second dimension.

23. The method of claim 18, wherein the second 2-dimensional DFT vector is offset by a factor = kO from the first 2-dimensional DFT vector in the first dimension and by a factor m1= q02from the first 2-dimensional DFT vector in the second dimension where k and q are positive integers, 01is an oversampling factor associated with the first dimension, and 02is an oversampling factor associated with the second dimension.

24. The method of any of claims 18-23, wherein orthogonal 2-D precoding vectors are applied for different layers with port splitting along one of the dimensions.

25. The method of any of claims 18-24, wherein the second 2-dimensional DFT vector orthogonal to the first 2-dimensional DFT vector,is determined as follows:m, where wherein k is an integer k > 1.

26. The method of claim 25, wherein the value of = kO1wherein k is an integer k > 1 is pre-defined in 3GPP specifications.

27. The method of any of claims 25-26, wherein the 2-D precoding vector applied to the second antenna group is given asmwhere 9pis the inter-antenna group co-phasing factor.

28. The method of any of claims 18-24, wherein the second 2-dimensional DFT vector orthogonal to the first 2-dimentional DFT vector,is determined as follows: vLi^m+m, where m1= q02wherein q is an integer q > 1.

29. The method of claim 28, wherein the value of m1= q02wherein q is an integer q > 1 pre-defined in 3GPP specifications.

30. The method of any of claims 18-29, wherein the 2-D precoding vector applied to the second antenna group is given as 9pvti m+miwhere 9pis the inter-antenna group co-phasing factor.

31. The method of any of claims 18-30, wherein the second 2-dimensional DFT vector orthogonal to the first 2-dimentional DFT vector,is determined as follows:,wherein k and q are integers k > 1, q > 1.

32. The method of claim 31, wherein the values of= kO1and m1= q02wherein k and q are integers k > 1, q > 1 pre-defined in 3GPP specifications.

33. The method of any of claims 31-32, wherein the 2-D precoding vector applied to thesecond antenna group is given as 9pvt>+l m+miwhere 9pis the inter-antenna group co-phasing factor.

34. The method of any of claims 18-33, wherein there are more than two antenna groups and where the number of antenna groups is Ngroupfor a given type of grouping, the number of interantenna group co-phase factors for that type of grouping is Ngroup— 1.

35. A User Equipment, UE, (1000) comprising processing circuitry (1002) and memory (1010), the memory (1010) comprising instructions to cause the UE (1000) to: determine a first 2-dimensional Discrete Fourier Transform, DFT, vector applied to a first antenna group withports in a first dimension and N2ports in the second dimension; determine an inter-antenna group co-phasing factor along with a second 2-dimensional DFT vector applied to a second antenna group with N1ports in a first dimension and N2ports in the second dimension; report the first 2-dimensional DFT vector, the second 2-dimentional DFT vector, and the inter-antenna group co-phasing factor to a network node as part of precoder matrix indicator feedback.

36. The UE (1000) of claim 35 further operable to implement the features of any of claims 2- 17.

37. A computer-readable medium comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any one of claims 1 to 17.

38. A network node (1100) comprising processing circuitry (1102) and memory (1104), the memory (1104) comprising instructions to cause the network node (1100) to: for a first spatial layer, determine a first 2-dimensional DFT vector applied to the first antenna group, with N1ports in a first dimension and N2ports in the second dimension, and the ports along one of the first or second dimension is split into a first antenna group and a second antenna group; determine a first inter-antenna group co-phasing factor along with the first 2-dimensional DFT vector applied to the second antenna group; for a second spatial layer, determine a second 2-dimensional DFT vector applied to thefirst antenna group; and determine a second inter-antenna group co-phasing factor along with the second 2- dimsional DFT vector applied to the second antenna group.

39. The network node (1100) of claim 38 further operable to implement the features of any of claims 19-34.

40. A computer-readable medium comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any one of claims 18 to 34.

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