Codebook-based beamforming in o-ran radio unit

Abstract

According to some embodiments, a method is performed by an open radio access network (O-RAN) radio unit (O-RU) for codebook-based dynamic beamforming. The method comprises: receiving, from an O-RAN distributed unit (O-DU), control plane information comprising: a port- to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports. The method further comprises: receiving user plane information from the O-DU for transmission to a wireless device; generating a beamforming weight matrix for the wireless device based on the port-to-antenna mapping, codebook description, and spatial configuration; and transmitting the user plane information to the wireless device according to the generated beamforming weight matrix.

Description

Codebook-Based Beamforming in ORAN Radio Unit TECHNICAL FIELD

[0001] Embodiments of the present disclosure are directed to wireless communications and,more particularly, to codebook-based beamforming in an open radio access network (O-RAN) radio unit. BACKGROUND

[0002] In fourth generation (4G) Long Term Evolution (LTE) and fifth generation (5G) NewRadio (NR), massive multiple input multiple output (MIMO) is a key enabler for improved spectral efficiency. MIMO facilitates reusing the same frequency and time resources simultaneously for multiple user layers, from same or multiple user equipment (UE). Massive MIMO involves deploying array antennas with a large number of array elements; typically much larger than the number of user layers, for example, 64 antennas supporting a maximum of 8 or 16 user layers. Massive MIMO is often referred to as massive beamforming and can form narrow beams, focusing the received or transmitted signal in different directions.

[0003] Beamforming in uplink (UL) can be based, e.g., on channel estimation of latestreceived sounding reference signals (SRS) or demodulation reference signals (DMRS) in same slot as the uplink data. In downlink (DL), beamforming may be based on uplink channel measurement if the channel can be considered reciprocal, which is applicable for time-division duplexing (TDD) operation. Another alternative, which does not rely on uplink channel measurements, and thus also works for frequency-division duplexing (FDD), is codebook-based beamforming based on UE feedback after measurement of channel state information reference signals (CSI-RS) received from a base station. The codebook-based beamforming is considered herein.

[0004] For DL transmission, the base station allocates CSI-RS to resource elements (REs)using a combination of multiplexing techniques: in time (TDM), frequency (FDM), and / or code (CDM). Third Generation Partnership Project (3GPP) uses specific antenna port (AP) (a logical designation by 3GPP) numbers starting at 3000 for CSI-RS in 5G NR. In LTE and 5G NR, up to 32 APs are supported for CSI-RS (i.e., 32 CSI-RS ports), but some UEs have a restriction and can only support, e.g., up to 8 port CSI-RS.

[0005] Figure 1 illustrates an example of 8-port CSI-RS allocation in a resource block / slotgrid of REs. The horizontal axis represents the 14 orthogonal frequency division multiplexing (OFDM) symbols in a slot while the vertical axis represents the 12 resource elements in a resource block. In the illustrated example, ‘A’ represents a CDM group of the first two antenna ports (AP3000–3001 in 5G NR), ‘B’ is a CDM group of AP 3002–3003, and so on. In this example, FDM is used between A and B (also between C and D), while TDM is used between A and C (also between B and D). Empty squares in Figure 1 may be idle or contain, e.g., downlink user data, common control signals, or other reference signals.

[0006] A UE in, e.g. 5G NR, can be requested to report CSI, such as channel quality indicator(CQI) (used, e.g., for link adaptation), rank indicator (RI) (channel rank, i.e., maximum number of transmission layers), layer indicator (LI) (indicates the best-quality layer among the RI layers) and precoding matrix indicator (PMI) based on reception of CSI-RS signals transmitted by a base station. The RI / PMI together indicate a preferred downlink precoder from codebooks specified by 3GPP and known by both the UE and gNB. From RI and PMI, the base station can calculate necessary DL beamforming (precoding) weights per user layer, to apply to DL user data before transmission. In some contexts, precoding is the same as DL beamforming, while in other cases precoding is considered a part of the DL beamforming. Herein, precoding denotes the mapping from user layers to CSI-RS ports.

[0007] The gNB can, via a DL control channel, configure what codebook type to use (e.g.,Type I single / multi panel or Type II variants) and impose restrictions on what the UE can select (e.g., restricted subsets of codebook indices). The UE report indicates channel rank and a preferred precoder from a standardized codebook. The preferred precoder can contain a wideband part X1describing a subset of beams to use and a subband part X2, which can refine beam selection further, adjust phase between polarizations, and / or adjust magnitude (magnitude control is only available in Type II). For 5G NR, there can be up to 19 subbands in a CSI report. The CSI reporting subbands are aligned with the 3GPP common resource block (CRB) grid, which has a common reference point known as point A. Reference point A coincides with subcarrier 0 of common resource block 0 for all subcarrier spacings. The physical resource blocks (PRBs) of a bandwidth part (BWP) scheduled by the gNB for a particular UE may have an offset to the CRB grid.

[0008] Most 5G NR codebooks are based on one or two-dimensional spatial discrete Fouriertransforms (DFT) per polarization. A uniform dual-polarized planar antenna array with N1 columns and N2 rows is assumed, as illustrated in Figure 2.

[0009] Figure 2 illustrates a dual-polarized array of CSI-RS (antenna) ports for codebooks in,e.g., 5G NR. The horizontal and vertical dimensions can be oversampled in the DFT (typically by a factor of 4) to create a finer-grained beam grid. For multiple panels, each panel has an array with the same size.3GPP does not define which of N1 and N2 is horizontal, and which is vertical because it is not important for the UE, but it is often assumed that N1 represents horizontal because 3GPP supports larger values for N1 (no configuration has N2>N1) and massive MIMO arrays typically have more elements in the horizontal direction.

[0010] Many different such antenna (N1, N2) array configurations are supported in 5G NR(and LTE). Table 1 below shows possible combinations for Type I single-panel and multi-panel codebooks in 5G NR for different number of CSI-RS ports (PCSI-RS). Type II codebooks support same configurations as Type I single-panel. Other combinations of configurations are available for LTE codebooks. The number of polarizations is two, which gives PCSI-RS = 2N1N2. Parameters O1 and O2 represent codebook spatial (angular) oversampling in vertical and horizontal (or horizontal and vertical) direction, respectively.

[0011] Oversampling does not create more orthogonal beams but allows fine-tuning beamdirections. As an example for single panel, if (N1, N2) = (4, 2), then (O1, O2) = (4, 4) and there will be 4×4=16 horizontal beams and 2×4=8 vertical beams.

[0012] Note that PCSI-RS=2* is a special case from 3GPP TS 38.214 Table 5.2.2.2.1-1 where(N1, N2) and (O1, O2) are not given by 3GPP, but it was found that this case can be mapped to the values suggested in the table (reusing at least part of the implementation of other 3GPP Type I single-panel codebooks with codebookMode = 1 where beam indices i1,1 and i1,2 both become zero by definition with these N1, N2, O1, and O2values). For this special 2-port codebook, there is only one beam and the desired row (codebook index) with different phase for the second polarization can be selected using the subband index i2 (1 bit for 2-layer case, 2 bits for 1-layer case), avoiding the need for a dedicated field. Table 1. Type I single panel and multi panel codebook array configurations for 5G NR from Tables 5.2.2.2.1-2, 5.2.2.2.1-2, and 5.2.2.2.2-1 in TS 38.214, except for PCSI-RS=2, which uses a codebook from table 5.2.2.2.1-1 with a special mapping. Type I single panel Type I multi panel (Ng, N1, PCSI-RS (N1, N2) (O1, O2) PCSI-RS (O1, O2) N2) 2* (1, 1) (1, 1) 8 (2, 2, 1) (4, 1) 4 (2, 1) (4, 1) (2, 4, 1) (4, 1) (2, 2) (4, 4) 16 (4, 2, 1) (4, 1) 8 (4, 1) (4, 1) (2, 2, 2) (4, 4) (3, 2) (4, 4) (2, 8, 1) (4, 1) 12 (6, 1) (4, 1) (4, 4, 1) (4, 1) 32 (4, 2) (4, 4) (2, 4, 2) (4, 4) 16 (8, 1) (4, 1) (4, 2, 2) (4, 4) (4, 3) (4, 4) 24 (6, 2) (4, 4)(12, 1) (4, 1) (4, 4) (4, 4) 32 (8, 2) (4, 4) (16, 1) (4, 1)

[0013] Figure 3 illustrates an example for DL transmission in a base station using CSI-RS andcodebook-based precoding. The example illustrates part of downlink precoding in a base station using codebook-based precoding and (optional) mapping of CSI-RS ports to array elements.

[0014] The CSI-RS are injected after the precoding block. An antenna array may have moreelements than the number of CSI-RS ports (5G NR supports up to 32 ports but some UEs may be limited to, e.g., 8 ports), especially for massive MIMO. Thus, mapping CSI-RS ports to array elements is necessary to facilitate using all array-elements (and power amplifiers) for the transmission. Such mapping may be simple (copy one- to-many) or include beamforming that enables adjusting the direction (tilt / pan) of the sector and / or adjusting the shape.

[0015] When the base station has a lower-layer split (LLS) with a fronthaul interface betweenbaseband processing (also referred to as distributed unit or digital unit (DU)) and radio unit (RU), such as Open Radio Access Network (O-RAN) WG4 (Open Fronthaul Interfaces) LLS (here called O-LLS), precoding can be done either in the DU (Category A) or in the RU (Category B). If precoding is performed in the RU, and the RU supports it, the beamforming weights are sent over fronthaul between DU and RU. In O-RAN, the baseband processing unit is denoted O-DU and the radio unit is denoted O-RU. Although specific examples are given for O-RAN LLS with O-DU and O-RU, the principles described herein are not necessarily limited to O-RAN LLS, but may also be used for other splits and interfaces, including proprietary ones.

[0016] O-LLS uses a data-associated control interface where user data (U-Plane) messagesare preceded by real-time control (C-Plane) messages. The C-Plane is based on different section types (ST) that may, e.g., provide scheduling information and beam ID or user (layer) ID for beamforming purposes. Existing section types may be extended with new functionality usingappended section extensions (SE) ), which may be specific to a subset of section types. C- / U-Planemessages are sent to / from “endpoints,” which are typically identified by an extended antenna carrier (eAxC) ID. As an example, each downlink user layer and uplink spatial stream would have a dedicated endpoint in the O-RU. There may also be one or more specific endpoints defined for other purposes, e.g., for channels like SRS and CSI-RS. O-RU capabilities and O-DU configuration of the O-RU are handled via management plane (M-Plane).

[0017] Examples of O-LLS C-Plane section types (sent from O-DU to O-RU) are shown inthe table below.Section Typical usage Type 0 Inform about unused resource blocks or unused symbols in DL / UL 1 Scheduling information, including beam ID, for most radio channels DL / UL 3 Physical random access channel (PRACH) with different numerology than UL, and mixed-numerology channels 4 Slot configuration control 5 Scheduling information, including UE ID (user ID, which is actually a layer ID)

[0018] Examples of O-LLS C-Plane Section Extensions are in the following table:Section Typical usage Extension 1 Beamforming weights (one vector with K weights) 2 Beamforming attributes 3 Downlink precoding parameters (for LTE TxD and CDD) 10 Multiple ports grouping 11 Flexible beamforming weights (K weights per PRB bundle) 14 Nulling-layer info for ueId based beamforming 16 Antenna mapping for UE channel information based UL BF 19 Compact beamforming information for multiple ports (K weights per port)

[0019] Further, in O-LLS, non-real-time configuration such as carrier configuration, etc. ishandled by a management interface (M-Plane). M-Plane is also used to inform about O-RU capabilities, e.g., support for different features.

[0020] O-RU is used herein to denote a radio unit while O-DU is used to denote a distributedunit or baseband unit.

[0021] There currently exist certain challenges. For example, O-LLS includes a C-Planesection extension, SE 3, intended for LTE precoding, but it can only support LTE precoding methods transmit diversity (TxD) and spatial multiplexing with cyclic delay diversity (CDD). The section extension does not work with, e.g., (N1, N2)-based codebooks.

[0022] To transmit CSI-RS in O-LLS today requires PCSI-RS beam IDs, each corresponding toK beamforming weights (BFWs) where K is the number of Tx array elements in the O-RU and PCSI-RS = 2N1N2 is the number of CSI-RS ports used. Altogether, the BFWs for the CSI-RS ports for a single (N1, N2)-configuration may be viewed as a matrix, Wp2awith K rows and PCSI-RScolumns. The weights may be sent over C-Plane using weight-based dynamic beamforming (WDBF) (e.g., using SE 19) but this either generates a significant amount of C-Plane traffic (if sent frequently) or requires storage in the O-RU. The weights may also be pre-defined in M-Plane, but this still requires storage in the O-RU and offline information is needed for the O-DU to know which beamId to use for a particular codebook beam.

[0023] If weights are stored, each supported (N1, N2)- configuration requires a unique set ofbeam IDs and beam weights, i.e., a unique BFW matrix. Multiple (N1, N2) configurations may be needed, e.g., because a large number of CSI-RS ports enables better precoding (allowing narrower and more precise beams), but as described above, not all UEs support the maximum number of CSI-RS ports.

[0024] Today, Type I and Type II codebook beamforming in an O-RAN Category B O-RU(Category B means that the O-RU is capable of DL precoding) must be handled via beam IDs, which has some limitations and problems. The limitations and problems may be handled in different ways in an O-RAN Cat B O-RU.

[0025] One way is mapping all possible codebook entries to individual beam IDs and storingthem in the O-RU, e.g., via M-plane configuration. The table will be large and will consume a significant part of the beam ID address space. For some cases, the 15-bit beam ID supported in O- LLS will not suffice, which means that not all codebook entries can be supported. Further, not all UEs can support the same codebook, e.g., the largest codebook. This depends on the UE capability. For example, in the field, some UEs support the largest 32-port codebook, while some other UEs with lower capability only support the codebooks with fewer ports. The O-RU needs to support all these UEs by supporting multiple configurations of (N1, N2) corresponding to the number of ports the UEs support. In this case, the number of codewords (codebook entries) needed will be the sum of the codewords of the codebooks of the number of supported (N1, N2) configurations, which makes the problem even worse. Further, in Release 19, 3GPP will increase the number of CSI-RS ports up to 128, which makes the predefined case even more infeasible.

[0026] Another way is using WDBF to send BFWs per antenna and layer from O-DU to O-RU. The resulting BFW matrix W to send from O-DU is the result of a matrix multiplication between the codebook BFW matrix Wpmiand Wp2a. This matrix multiplication must be performed in the O-DU before sending weights. Using WDBF for codebook-based BF can generate a significant amount of C-plane traffic, especially for massive MIMO. Further, with sub-band PMI, up to 18 BFW matrices may be needed (one vector per layer) for a single 5G NR carrier. 18×ν beamIds, each with K complex BFWs need to be conveyed to the O-RU, where ν represents the number of layers and K is the number of array elements. For NR100 with 8 layers and 64 array elements, this means up to 9216 BF weights for a single UE in one slot.

[0027] Because RI / PMI reporting from the UE is not done every slot, it may be desired tostore a codebook for reuse in multiple slots when the base station has a large amount of data to send to the UE. If the O-RU chooses to store codebooks for several connected UEs for later use (to avoid recalculating weights from PMI), many beam IDs and BFWs may be needed. SUMMARY

[0028] As described above, certain challenges currently exist with beamforming in an openradio access network (O-RAN) radio unit (O-RU). Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, in particular embodiments the O-RAN lower-layer split (LLS) real-time control (C-Plane) protocol is enhanced to enable more efficient sending and / or storage of information needed for mapping from channel state information reference signal (CSI-RS) ports to Tx array elements. This may be done, e.g., as a new O-RU capability, a new beamforming method (e.g., codebook-based dynamic beamforming (CDBF)), a new section extension (or a modified variant of an existing SE, e.g., SE 19, a new section type, or a new command in an existing section type (e.g., ST 4).

[0029] Mapping from CSI-RS ports to Tx array elements is needed both when transmittingCSI-RS from the O-RU to the UE, and for the output of the codebook-based precoder. Different methods may be used to describe the mapping in those two cases, but in general it is beneficial that the result of the mapping is the same. For example, if beamforming is applied to CSI-RS during transmission, then the same beamforming should be applied to the output of the precoder, although it might have been described in another way. An exception may be, e.g. array tapering, which may be used when transmitting codebook-precoded data but perhaps not on CSI-RS.

[0030] The C-Plane protocol is also enhanced to allow sending rank indicator (RI) / precodingmatrix indicator (PMI) codebook information including beam indices and co-phasing information, optionally also magnitude information, from O-RAN distributed unit (O-DU) to O-RU. Information related to signal quality, such as the user equipment (UE)-reported channel quality indicator (CQI) or signal-to-noise ratio (SNR) information may also be useful to send from the O- DU to O-RU. The signal quality information may be used, e.g., for regularization or other methods that help to produce more robust precoders, especially for multiple input multiple output (MIMO) involving matrix inverses. The sending of C-Plane information may be done in one or more new section extensions, herein referred to as SE “PMI” (where “PMI” may be replaced by an available number). Instead of a new SE, some embodiments may convey the information using a new beamforming method, a new section type, or a modification of an existing message, such as adding a new command to section type 4 (slot configuration control).

[0031] Mapping of CSI-RS ports (when sending CSI-RS or as output from the PMI precoder)to a physical Tx array exposed by the O-RU is referred to as port-to-antenna mapping (p2aMapping) and may be done in different ways, as described later. The (N1, N2) array assumed in 3GPP codebook design is seen as a logical array and does not necessary reflect the actual Tx array configuration, especially for massive MIMO radios with large number of array elements. It is possible to change the mapping, e.g., to use different tilt / pan angles, or to change cell shape, including reduction of beam magnitude in certain directions. It is also possible to control tapering of the logical array and / or the Tx array: either explicitly with dedicated bits to enable / disable or select between a few variants, or by changing the mapping from CSI-RS ports to the Tx array. Tapering can help to reduce sidelobes in directions away from the desired UE. This can reduce interference and / or enable multiple user (MU)-MIMO operation.

[0032] In some embodiments, it may be beneficial to use frequency-dependent p2aMappingwithin a carrier, i.e., a first range of physical resource blocks (PRBs) use one p2aMapping, a second range of PRBs use a different p2aMapping, etc. This may be useful, e.g., to mitigate beam squint where the beam focus can be different for different frequencies when phase shift instead of true time-delay is used to steer a beam. It can also be used to control tapering for only part of the PRB range.

[0033] Some embodiments include a pre-precoder placed before the RI / PMI determinedcodebook precoder, to facilitate control of how the layers are sent on the beams indicated by the PMI. This pre-precoder may be implemented as a matrix multiplication where the number of rows equals the rank indication and the number of columns equals the actual number of layers sent by the O-DU. One example is if, e.g., the UE reports rank 2 or higher for Type I single-panel PMI (which means that PMI indicates two beams for both polarizations), but the gNB only wants to send a single layer. Then, the pre-precoder facilitates splitting the power of that layer and sending it on both beams for both polarizations, which may make communication more robust.

[0034] In general, particular embodiments apply to base stations with a lower layer split(LLS), e.g., O-LLS, and precoding in radio unit (e.g., O-RAN Category B O-RU with 8 or more antennas as part of a dual-polarized array), based on UE reporting (mainly for codebooks based on N1×N2dual-polarized array of CSI-RS ports and using Fourier-related transforms, or eigen- based transforms).

[0035] When transmitting CSI-RS from the base station to a UE (to enable the UE to measureand report CSI), particular embodiments include more efficient description of the mapping between CSI-RS ports and Tx array elements (or number of transmit chains, i.e., TRX ports with individual digital-to-analog converters) than existing beamforming methods in O-LLS (predefined beams with beam ID, WDBF).

[0036] One example is when the mapping of CSI-RS ports may be described as uniformdisjoint rectangles, where a single beamforming weight vector and associated beamId may be used to represent the mapping from all CSI-RS ports to the Tx array. Another example is when the mapping is described as tensor products.

[0037] Same / similar methods may also be used to describe the mapping from the output ofthe precoder to Tx array elements.

[0038] When transmitting user data, particular embodiments include the followinginteractions between O-DU and O-RU.

[0039] In some embodiments, the O-RU describes (e.g., via management plane (M-Plane)) itssupported spatial configurations (e.g., N1, N2, and information about which of N1 and N2 is rows and columns). The description may optionally also include O1, O2because those can vary between radio access technologies (like Long Term Evolution (LTE) and New Radio (NR)).

[0040] In some embodiments, the O-DU may preconfigure (via M-Plane to the O-RU) a listof which spatial configurations the O-DU plans to use. This may enable the O-RU to optimize its resource usage.

[0041] In some embodiments, the O-RU describes (e.g., via M-Plane) which codebook typesthe O-RU supports. Codebook types may be subsets of Third Generation Partnership Project (3GPP) defined types, e.g., one codebook type may be Type I single-panel with codebookMode = 1. The description of a supported codebook may also include maximum supported rank, maximum number of CSI-RS ports, and maximum number of subbands for the type.

[0042] In some embodiments, the O-DU may preconfigure (via M-Plane to the O-RU) a listof which codebooks the O-DU plans to use. This may enable the O-RU to optimize its resource usage.

[0043] In some embodiments, the O-DU indicates (via C-Plane) which spatial configurationto use for a particular user layer (or set of user layers) in a slot. The spatial configuration may be needed by the O-RU both for the precoder and for the port-to-antenna mapping. The indication may be an index (pointer) into the O-DU preconfigured list in the O-RU. By pointing to the list of used spatial configurations, fewer bits in C-Plane might be needed than if pointing to the O-RU supported list.

[0044] In some embodiments, the O-DU describes (via C-Plane) the precoder to use for aparticular user layer (or set of user layers) in a slot. The description may include codebook type (e.g., pointer to the M-Plane defined list of types) and wideband, X1, and sub-band, X2, parts (with beam selection and co-phasing factors and optionally also amplitude weighting factors).

[0045] In some embodiments, the O-RU calculates a UE-specific beamforming weight (BFW)matrix from the received information. The calculation may include combining a wideband BFW matrix W1 and a sub-band BFW matrix W2.

[0046] In some embodiments, the O-DU describes (via C-Plane) the mapping from CSI-RSports to Tx array elements (needed at least if the number of CSI-RS ports is smaller than the number of Tx array elements in the RU) to use for a particular user layer (or set of user layers) in a slot. The O-Du may describe the mapping using beam IDs (one beam ID and / or K-element BFW vector per CSI-RS port and / or BFWs) or alternatively using other methods as proposed herein (e.g., one or more of beam group ID, bit mask, index list, range, tensor, short BFW vector / array, or attributes).

[0047] Optionally, different mappings may be used for different PRB ranges, e.g., to be ableto mitigate beam squint. This may be done, e.g., by having a list including a PRB block size, a beam ID for that block, followed by a new PRB block size with a beam ID, etc. until all PRBs covered by the scheduling information are covered.

[0048] In some embodiments, the O-RU may combine the UE-specific BFW matrix (fromcodebook description) with the port-to-antenna mapping to create a beamforming matrix to apply to U-Plane data.

[0049] Optionally, additional information is sent per PRB range (typically in conjunction withdescription of the precoder or port-to-antenna mapping) to enable tapering of the logical array, such as a flag enabling a pre-defined tapering, an index to pre-defined tapering functions, a matrix with tapering weights, or replacing the mapping from CSI-RS ports to Tx array elements with a mapping that includes tapering. Such tapering may reduce intercell interference and / or enable MU- MIMO with RI / PMI-based BF by reducing sidelobes of beams. Different UEs may be served simultaneously provided that their beams are sufficiently separated (low-enough correlation between beams).

[0050] Optionally, an explicit power scaling parameter is sent per PRB range, eitheroverriding or in addition to inherent scaling of the codebook. This power scaling may be useful if MU-MIMO is used for part of the PRB range occupied by a specific UE. Such scaling may be done by the O-DU on U-Plane IQ samples, but if e.g., modulation compression is used in the downlink, it might require many different modulation compression scale factors. In that case, it may be more efficient to perform the scaling in the O-RU based on information, e.g., in SE “PMI”.

[0051] Optionally, signal quality information is sent, e.g. channel quality indicator (CQI), toenable more robust MIMO precoding, e.g. for MU-MIMO with Type II codebooks.

[0052] Optionally, information about a “pre-precoder” is conveyed, to enable changing howlayers are applied to beams of the codebook. This may be represented as a matrix where the numberof rows equals the reported rank, and the number of columns equals the actual number of layers transmitted. If all layers are transmitted according to the UE reported rank and PMI, the pre- precoder becomes an identity matrix. For single-layer transmission using both beams of the rank- 4 codebook specified in the upper half of 3GPP TS 38.214, Table 5.2.2.2.1-8, the pre-precoder matrix may be e.g., [√0.5 √0.500]Tbecause the first two columns of the codebook precoder use different beams (columns 1 and 3 use one beam while columns 2 and 4 use another beam). HereTindicates matrix transpose.

[0053] According to some embodiments, a method is performed by an O-DU network nodefor codebook-based dynamic beamforming. The method comprises transmitting, to an O-RU, control plane information comprising: a port-to-antenna mapping that maps logical (e.g., CSI-RS) ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports. The method further comprises transmitting user plane information to the O-RU, the user plane information to be transmitted by the O-RU to a wireless device according to the port-to-antenna mapping, codebook description, and spatial configuration.

[0054] In particular embodiments, the method further comprises receiving from the O-RU anindication of spatial configurations supported by the O-RU. The method may further comprise transmitting to the O-RU an indication of one or more spatial configurations that the O-DU intends to use. The spatial configuration may comprise a number of rows and columns in the logical array of logical (e.g., CSI-RS) ports. The spatial configuration may further comprise an indication of discrete Fourier transform beam oversampling in each of vertical and horizontal directions for the logical array of logical ports.

[0055] In particular embodiments, the control plane information further comprises anindication of a codebook type.

[0056] In particular embodiments, the method further comprises receiving from the O-RU anindication of codebook types supported by the O-RU. The method may further comprise transmitting to the O-RU an indication of one or more codebook types that the O-DU intends to use. The codebook type may comprise an indication of one or more of a maximum supported rank, a maximum number of CSI-RS ports, and a maximum number of subbands for the type. The codebook description may further comprise a wideband part and a subband part.

[0057] In particular embodiments, each logical port of the array of logical ports is mapped toa disjoint rectangle of antennas in the physical transmit array and wherein the port-to-antenna mapping comprises a single beamforming weight vector and associated beam identifier mapping all logical ports to the physical transmit antenna array.

[0058] In particular embodiments, the port-to-antenna mapping comprises one beam formingweight tensor for a vertical direction of the physical antenna array and one beam forming weight tensor for a horizontal direction of the physical antenna array.

[0059] In particular embodiments, the port-to-antenna mapping comprises more than oneport-to-antenna mapping each associated with a different frequency range.

[0060] In particular embodiments, the control plane information further comprises any one ormore of: a power scaling parameter; a tapering parameter; signal quality information; and an indication of a pre-precoder.

[0061] According to some embodiments, a method is performed by an O-RU for codebook-based dynamic beamforming. The method comprises receiving, from an O-DU, control plane information comprising: a port-to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports. The method further comprises: receiving user plane information from the O-DU for transmission to a wireless device; generating a beamforming weight matrix for the wireless device based on the port-to-antenna mapping, codebook description, and spatial configuration; and transmitting the user plane information to the wireless device according to the generated beamforming weight matrix.

[0062] According to some embodiments, a network node comprises processing circuitryoperable to perform any of the methods of the network nodes described above.

[0063] Also disclosed is a computer program product comprising a non-transitory computerreadable medium storing computer readable program code, the computer readable program code operable, when executed by processing circuitry to perform any of the methods performed by the network nodes described above.

[0064] Certain embodiments may provide one or more of the following technical advantages.For example, particular embodiments include significant reduction of C-plane traffic because there is no need to send beamforming weights per user layer and subband. Also, sending or storing a large matrix of BFWs for mapping from CSI-RS ports to Tx array elements may be avoided.

[0065] Another advantage is that significantly fewer beam IDs are needed. There is no needto reserve a large range of beam IDs for full codebook and no need to store and send separate beam ID per subband when PMI is updated dynamically.

[0066] Other advantages may be readily apparent to one having skill in the art. Certainembodiments may have none, some, or all of the recited advantages.BRIEF DESCRIPTION OF THE DRAWINGS

[0067] For a more complete understanding of the disclosed embodiments and their featuresand advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: Figure 1 illustrates an example of 8-port channel state information reference signal (CSI- RS) allocation in a resource block / slot grid of resource elements (REs); Figure 2 illustrates a dual-polarized array of CSI-RS (antenna) ports for codebooks in, e.g., fifth generation (5G) New Radio (NR); Figure 3 illustrates an example for downlink (DL) transmission in a base station using CSI- RS and codebook-based precoding; Figure 4 illustrates an example of open radio access network (O-RAN) radio unit (O-RU) downlink precoding and port-to-antenna mapping; Figure 5 illustrates an example of disjoint uniform mapping from 16 CSI-RS ports to a 64- element tx-array when N2represents rows; Figure 6 illustrates an example of disjoint uniform mapping from 16 CSI-RS ports to a 64- element 64 Tx-array when N2 represents columns; Figure 7 illustrates an example communication system, according to certain embodiments; Figure 8 illustrates an example UE, according to certain embodiments; Figure 9 illustrates an example network node, according to certain embodiments; Figure 10 illustrates a block diagram of a host, according to certain embodiments; Figure 11 illustrates a virtualization environment in which functions implemented by some embodiments may be virtualized, according to certain embodiments; Figure 12 illustrates a host communicating via a network node with a UE over a partially wireless connection, according to certain embodiments; Figure 13 is a flowchart illustrating an example method performed by an O-RAN distributed unit (O-DU) network node, according to certain embodiments; and Figure 14 is a flowchart illustrating an example method performed by an O-RU network node, according to certain embodiments. DETAILED DESCRIPTION

[0068] As described above, certain challenges currently exist with beamforming in an openradio access network (O-RAN) radio unit (O-RU). Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, in particular embodiments the O-RAN lower-layer split (LLS) real-time control (C-Plane) protocol is enhancedto enable more efficient sending and / or storage of information needed for mapping from channel state information reference signal (CSI-RS) ports to Tx array elements.

[0069] Particular embodiments will now be described more fully with reference to theaccompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0070] When transmitting CSI-RS, signal injection is done to the CSI-RS antenna ports(logical array) after the precoding block. This is illustrated in the example in Figure 4 where each CSI-RS port (one element in the logical array) maps to a group of elements with the same polarization in the Tx array. This is a common mapping scheme and the mapping may include beamforming. In this example, dimension N2 represents rows of the logical array.

[0071] Figure 4 illustrates an example of O-RU downlink precoding and port-to-antennamapping. In this example, each element in the logical array maps to a unique set of (M / N2)×(N / N1) elements in the Tx array. The number of elements in the Tx array is K=M×N×2.

[0072] Each O-RU carrier is associated with layer endpoints corresponding to the maximumnumber of layers supported, e.g., 8 (for single user multiple input multiple output (SU-MIMO)), or 16 (for multiple user (MU)-MIMO, using one precoder per user and adding outputs of the precoders). The maximum number of layers may depend, e.g., on O-RU processing capability and on the number of array elements in the antenna. How the layers are mapped to the precoder may be explicitly or implicitly communicated to the O-RU from the O-DU.

[0073] Further, an O-RU carrier can be associated with additional endpoints for CSI-RS. Thenumber of endpoints needed may depend on the code division multiplexing (CDM) used for CSI- RS. In O-RAN LLS, if 32 CSI-RS ports are used and CDM2 is applied, up to 16 CSI-RS ports (in the same CDM group) may be described in one C-Plane message with one eAxC when section extension 19 is used.

[0074] Mapping from CSI-RS ports to Tx array may be done, e.g., by different beam ID setsfor different number of CSI-RS ports (and different configurations for the same number of ports). Note that Third Generation Partnership Project (3GPP) numbers CSI-RS ports first over N2 then over N1, while O-RAN numbers array elements from left to right and from bottom to top. If a dedicated beam ID with corresponding K beamforming (BF) weights is used for each CSI-RS port and a disjoint rectangular mapping is used, most of the weights will be zero.

[0075] In one type of mapping, each CSI-RS port maps to a rectangle of (M / N2)×(N / N1)single-polarized elements in the Tx array, while the rest of the weights are zero. For example, if a dual-polarized Tx array has size (8, 4) and the logical array has size (4, 1), then only (8 / 4)×(4 / 1)=2×4=8 weights for each beam ID are non-zero while 64-8=56 weights are zero. This facilitates more efficient sending and / or storing of beamforming weights (BFWs) than in existingO-LLS, reducing the total number of BFWs from 32×64=2048 weights to 32×8=256 weights plus some side information describing the mapping. The side information may be, e.g., in the form of bit masks indicating which array elements are included in the mapping for each CSI-RS port.

[0076] Some embodiments may use other mappings. For example, some embodiments mayuse a description of one or more ranges of non-zero weights, or a vector / array with one value per Tx array element indicating which CSI-RS port maps to that array element.

[0077] An observation is that all CSI-RS ports may have identical non-zero BFWs, but placedon different positions in the BFW vector (same beamforming applied to each CSI-RS port, which at least makes sense for regularly spaced rectangular arrays when no tapering is applied). Instead of sending and / or storing K×PCSI-RS weights, it may then be enough with (M / N2)×(N / N1) unique weights. With the same assumptions as in the example above, this means sending 8 BFWs plus some side information.

[0078] Yet another optimization may be available if vertical and horizontal beamforming areindependent in the mapping. In that case, it is enough to send one (M / N2)-element BFW tensor (in this case the tensors are BFW vectors) for the vertical direction and one (N / N1)-element tensor for the horizontal direction. The tensors may be combined to a 2D-matrix in the O-RU, by using a Kronecker product. The tensor approach requires sending (M / N2)+(N / N1) weights, which using the same example numbers as above results in 2+4=6 weights (plus side information), out of the original 2048.

[0079] Instead of sending BFW matrices or vectors, some embodiments may sendbeamforming attributes such as beam azimuth and elevation. Also in this case, some side information may be needed to describe the mapping.

[0080] Apart from the mapping from CSI-RS ports (logical array) to Tx array, someembodiments also describe the precoding matrix indicator (PMI)-based codebook. Here it is assumed that a new section extension, SE “PMI”, is defined in O-LLS for this purpose, but some embodiments may, e.g., define a new section type, or a new command in an existing section type such as ST 4.

[0081] Capability of supporting SE “PMI” may be specified per endpoint in M-Plane (e.g.,for each such endpoint, per array, or for the whole O-RU). The O-RU may indicate via M-Plane which codebook types it supports, and also any restrictions on the supported codebooks. The description of the precoder includes information related to downlink (DL) channel rank and indices selecting subsets of beams, co-phasing phase factors, and / or amplitude weighting factors from a codebook known by the UE. This information may, but does not have to, be the same as the rank indicator (RI) / PMI reported by the UE because an O-DU may override the RI / PMI. The information may be tagged with an identifier (beam ID, UE ID, a beam- / user-group ID, or someother type of ID) to be able to reuse the same precoder for multiple transmissions without re- calculating the codebook. The information may also include the number of CSI-RS ports.

[0082] In some embodiments, the O-RU via M-Plane declares the supported spatialconfigurations, e.g., a list of supported combinations of N1, N2(and optionally O1, O2), and, e.g., a flag to indicate rotation of the logical array of CSI-RS ports (e.g., whether N2 indicates rows or columns). As an alternative to the flag, some embodiments may indicate rotation when N2 > N1 but then the O-RU may need to swap the values and remember that the logical array is rotated. Declaration of supported spatial configurations may be done per (transmit) antenna array because the supported spatial configurations might depend on the number of rows and columns of the antenna array. There may be two rows with identical N1, N2, O1, O2, e.g., if the flag to indicate rotation differs. To enable the O-RU to save resources, the O-DU may configure a list of the spatial configurations the O-DU intends to use, e.g., as a list of indices to the supported spatial configurations. The O-RU may have a limit on the maximum number of enabled (used) spatial configurations.

[0083] In some embodiments, the O-RU via M-Plane declares supported codebook types andrelevant limits, e.g., as a list of {codebook-type, max-rank, max-csi-rs-ports, max-num-subbands}. Some embodiments may add information indicating the intended radio access technology, e.g., as an additional parameter in the list, or in the names of the codebook-type enumeration. The codebook-type may be according to a predefined enumeration, e.g., {NR-TYPE-I-SINGLE- PANEL-CBMODE-1, NR-TYPE-I-SINGLE-PANEL-CBMODE-2, NR-TYPE-II, NR-TYPE-II- ENHANCED,…}. The “CBMODE” part of the first two types corresponds to different settings of 3GPP higher layer parameter codebookMode (which can take a value of 1 or 2). The list of supported codebook types may have multiple entries of the same codebook-type, e.g., where one allows higher max-rank and one allows higher max-csi-rs-ports. Again, to allow the O-RU to save resources, the O-DU may configure a list of the codebook types the O-DU intends to use, e.g., as a list of indices to the supported ones. Also here, the O-RU may have a limit on the maximum number of enabled (used) codebook types.

[0084] If the O-RU knows which spatial configurations and codebook types that the O-DUintends to use, the O-RU may pre-calculate some of the codebook matrices during setup when the O-DU configures carriers, etc. This may facilitate reduced computational complexity when the C- Plane messages with the new section extension arrive. Here, the maximum number of used codebook types and spatial configurations may help the O-RU to conserve resources because the O-RU can force the O-DU to enable only a limited set.

[0085] Information sent from O-DU to O-RU, e.g., in SE “PMI”, may include (but is notlimited to) the following. The new section extension may be sent separately to each layer (e.g.,using least significant bits (LSBs) of ueId as layer index) or to a group of layers (e.g., using section extension 10 to group ueIds). ^Codebook identifier (optional)^ An explicit identifier in the SE is optional, but may make it easier to reuse an alreadydefined codebook (for a specific UE) without recalculating the beamforming weights from the RI / PMI information and / or without having to compare multiple parameters). As an alternative, some embodiments may use, e.g., the UE ID in the ST5 section description as an identifier. If persistent codebooks are not desired, then a codebook identifier is not needed in the information sent from the O-DU. ^Spatial configuration (spatialConfigIndex)^ An index into an M-Plane list of supported or used spatial configurations uses fewerbits than conveying explicit values of N1, N2(and optionally O1, O2), and e.g., a flag to indicate rotation of the logical array of CSI-RS ports in the SE “PMI”. The spatial configuration information may be needed both for the codebook and for the p2aMapping. ^Codebook description^ codebookType (provide index to desired type such as ‘typeI-SinglePanel’, or acodebookTypeIndex with indirect reference to a list defined in M-plane with supported or used codebook types). The M-Plane list may contain multiple entries of the same 3GPP codebook type but with different restrictions on maximum rank, maximum number of CSI-RS ports, or maximum number of subbands. ^Mode (e.g., parameter codebookMode for Type I, and subbandAmplitude for Type II).As an alternative, such parameters may be encoded by defining multiple entries of the same codebook type but with different value of the parameter. ^numSubbands (number of subbands, optional, may be derived if total number of PRBsand subband size are both known). ^firstSubbandSize (size of first subband, optional, but may be useful if the PRB grid inthe C-Plane message is not aligned with CRB grid). An alternative is to configure carrier offset to 3GPP defined “point A”, e.g., via M-Plane, to enable the O-RU to determine the offset between the CRB grid and the PRB grid. ^subbandSize (number of RBs per subband, support at least the following: 4, 8, 16, 32,‘wideband’, i.e., all RBs). The O-DU may decide to use a smaller subbandSize than the size used in UE CSI reporting, e.g., by interpolating or repeating per-subband codebook parameters. ^RI or rankInd^ Subband bit width (optional, number of bits to allocate per subband. Can be derivedfrom other parameters but stating it explicitly may simplify message parsing) ^X1 (wideband part of PMI), e.g., i1 indices in Type I single-panel^ X2 (subband part of PMI), e.g., i2 indices in Type I single-panel^ Scaling (optional), to override default power scaling in 3GPP codebooks, which isbased on rank and number of CSI-RS ports. ^Explicit Layer ID (optional)^ An explicit layer ID is optional, it is also possible to have implicit layer ID, e.g., usingLSBs of UE IDs, or based on the order of UE IDs ^Rank override (Optional, transmit with fewer layers than RI)^ Optional, could be e.g., a bit mask indicating which layers that has associated data inU-Plane, or a list of layers. Can alternatively be handled outside the SE “PMI”, e.g., by using a reserved value for UE ID, indicating that a specific layer will not have any data, or by using additional Section Extension(s), e.g., SE 10. May also be handled by separate sending of SE “PMI” only to the O-RU endpoints of the layers that will be used. ^Number of CSI-RS ports (optional, may be determined from the spatial configuration as2×N1×N2) ^Either as an explicit parameter, or implicit, based on other information such as thenumber of members in a beam group referred to in the mapping from CSI-RS ports to array elements ^Information regarding mapping from CSI-RS ports to Tx array elements^ Different options may be used as described below, e.g., based on beam ID. Includespossibility to have different mapping for different PRB ranges, e.g., by specifying pairs of PRB block size and beamId(s). ^Additional input for the mapping method

[0086] The mapping method and / or additional input for the mapping method do notnecessarily have to be present in the SE “PMI”, but may be conveyed in other ways. If a more efficient mapping (e.g., tensor approach) is implemented than what is available in the current CUS- plane specification when sending CSI-RS, it may be beneficial to have the mapping in a separate section extension, SE “MAP”, or e.g., as a beamforming method, instead of including it in SE “PMI”. The SE “MAP” may then be used both when sending CSI-RS and in combination with SE “PMI” when sending data layers.

[0087] Some embodiments include connecting UE layers to codebook information. ST 5 maybe used when sending PMI information in new SE “PMI.” The UE ID parameter ‘ueId’ in the section description represents a UE layer. More specifically, an M-Plane configurable number of LSBs may represent layers for one UE while remaining most significant bits (MSBs) may be used to enumerate UEs. Multiple layers per UE may be handled either by separate ST 5 plus SE “PMI” to each layer endpoint, or by grouping with SE 10 where ueIds for additional layers may be listed.

[0088] When sending PMI information to multiple layers at once, e.g., using SE 10, a specialvalue such as 0x7FFF (non-scheduled ueId in O-LLS) in SE 10 beamGroupType 10b may be used for rank override, indicating that a specific layer does not have any data. Another alternative is SE 10 beamGroupType 11b (introduced in CUS-Plane specification version 16.01,), which includes a list of indices to layers to use. Alternatively, SE 14 may be used to indicate “null layers”, i.e., layers where there is no corresponding U-Plane message but the O-RU fills in zeros. All layers in one invocation of the SE “PMI” belong to same UE so no need for e.g., SE 17.

[0089] For MU-MIMO, a separate ST5 and SE “PMI” may be sent per UE. One or more bitsin C-Plane, preferably in SE “PMI”, may be used to control tapering. Alternatively, tapering may be handled by changing p2aMapping. Some embodiments may control tapering per PRB range, for example, to enable tapering for PRB ranges where MU-MIMO is used and disable tapering otherwise to avoid unnecessary power loss.

[0090] An explicit power scaling parameter (optional) may be useful to reduce power per UEwhen MU-MIMO is used because the default codebook scaling in 3GPP assumes all power is used by one UE. The O-RU may determine the scaling without an explicit parameter but then the O- RU may need to wait for all C-Plane messages for a specific symbol to make sure that there is no additional user scheduled in the same PRB range. Alternatively, the O-DU may scale down IQ data samples in U-Plane to compensate. When modulation compression is used, this might require sending different modCompScaler parameters for different PRB ranges.

[0091] The O-RU may add the outputs of the precoders for different UEs and use a commonmapping from CSI-RS ports to Tx array elements. This requires that same (N1, N2) configuration is used.

[0092] The example usage below assumes that a new SE “PMI” is defined. Step 2 wouldchange if the RI / PMI information is sent in another way, e.g., as a new command in ST 4. The ability to reuse an already defined codebook without the need for the O-RU to calculate it again (step 4) is optional. If this is not desired (e.g., due to increased memory requirement in O-RU to store multiple precoding weight matrices), step 2 can be repeated for each DL transmission to same UE instead.1. Send CSI-RS to UE– Send C-plane^ using ST 1 and dedicated beam IDs (legacy O-LLS approach) for each CSI-RS port, or ^using, e.g., ST 1 (or ST 3) with a more efficient mapping (new approach),e.g., same beam ID for all CSI-RS ports and additional information according to alternatives for mapping from CSI-RS ports to Tx array elements, e.g., a new SE “MAP” with information about the mapping, a combination of section extensions, or using a new beamforming method. –Send U-plane for CSI-RS using existing O-LLS U-plane.– Later, O-DU receives CSI report with RI / PMI from UE, via existing O-LLS U-Planefrom the O-RU.Define RI / PMI-based codebook for a UE– Send ST 5 C-plane with RI / PMI codebook info and CSI-RS beam ID.– UE ID in ST 5 may be used to identify first layer.– SE “PMI” contains spatial configuration selection, codebook description (RI / PMI,etc.), port-to-antenna mapping and optional tapering control. –A separate C-Plane message with ST 5 and SE “PMI” may be sent to each layerendpoint in the O-RU that will be used for the codebook-based beamforming. The layer ID (e.g., LSBs of UE ID) must be different for the different layers, while part or all of the remaining information in SE “PMI” may be the same. –SE 10 can be used to group UE layers, e.g., beamGroupType 10b, optionally withnon-scheduled ueId for unused layers, or beamGroupType 11b with indices to select a subset from the list, or by using SE 14 nulling layer info if less than RI layers will be used. As an alternative, a modified SE 10 may also be used, including a bitmask. –Layer ID can be explicitly specified in the SE “PMI”, or implicitly, e.g., by usingleast-significant bits of UE ID, or by the order of UE IDs selected in SE 10. –Mapping from CSI-RS ports to Tx array either by, e.g., beam ID list, beam group IDin SE “PMI”, or using a separate SE “MAP”, or a new beamforming method. –Send associated U-plane if desired (and if available)– Using existing O-LLS mapping method between C-Plane and U-PlaneSend associated U-plane if desired (and if available)– Using existing O-LLS mapping method between C-Plane and U-PlaneOptionally reuse previously defined codebook for same UE (optional and assuming no newRI / PMI report, or alternatively using full step 2 above instead, avoiding storing the codebook in the O-RU)– Send ST 5 C-plane– The codebook defined in step 2 may be identified by existing ST 5 parameters such asUE IDs, which facilitates reusing the codebook for same UE without sending the SE “PMI” again. Another alternative is to include a dedicated codebook type in the SE “PMI” and send the SE “PMI” again, potentially a shorter variant skipping some information. –Sending the SE “PMI” also when reusing the previously defined codebook facilitatesmodifying certain parameters, e.g., enabling tapering of the logical array to reduce sidelobes for beams away from the UE. –SE 10 may be used to group UE layers, optionally with non-scheduled ueId forunused layers, or SE 14 nulling layer info if less than RI layers will be used. As an alternative, a modified SE 10 may also be used, including a bitmask or indices to select a subset from the list.5. Send associated U-plane for reused codebook– Using existing O-LLS mapping method between C-Plane and U-Plane

[0093] Some embodiments include codebook description for 5G NR. This may be used toidentify if different codebook types can share same information fields, or if it is better to have different information fields for different types. Similar method may be used to derive corresponding numbers for, e.g., LTE, or for 6G once available. Note that information fields other than the PMI-related parts shown below may also be used.

[0094] For 5G NR, the minimum number of bits necessary to describe the PMI can be foundin 3GPP TS 38.212 for different codebook types. The number of bits per field can vary with rank, number of CSI-RS ports, etc. However, when conveying the information over fronthaul from O- DU to O-RU, using fixed-size fields for each parameter (independent of rank and number of CSI- RS ports) may be beneficial to simplify parsing. Also, some of the fields may be made slightly larger than currently needed in 3GPP, to avoid changing open fronthaul specifications when there are minor changes to 3GPP defined codebooks.

[0095] For Type I single panel codebook with up to 32 CSI-RS ports, 12 bits are enough torepresent the X1 (wideband) part, consisting of three different indices where i1,1 maps to horizontal beam index, i1,1 to vertical beam index. 3GPP Release 19 will allow up to 128 ports, thus some embodiments may use slightly larger fields for future-proofness.

[0096] Further, for Type I single-panel codebook, the per subband part, X2, needs up to 4 bitsper subband with codebookMode = 2, and up to 2 bits per subband with codebookMode = 1. Here it is possible to either always allocate 4 bits to simplify message parsing, or to allow different bit width for different precoder configurations if it is more important to reduce message size than tosimplify message parsing. When different bit widths are used, they may be explicitly controlled via a dedicated subband bit width parameter, or implicitly controlled based on combinations of other parameters such as RI and codebookMode (CM1 or CM2). It may be beneficial to have separate codebook types defined for the two codebookMode values. Then an O-RU may declare support separately for them. The information about field sizes below is intended to illustrate differences between codebook types, and not to restrict the implementation in any way.● Wideband PMI (X1):– i1,1, i1,2, i1,3: 6 + 4 + 2 = 12 bits (some embodiments may allocate at least 16 bits: e.g.,8 + 5 + 2 + 1 spare bit)● Per-subband PMI (X2, up to 18 subbands)– i2 (CM1): 2 bits in rank 1, 1 bit otherwise (some embodiments may allocate 2bits / subband) –i2 (CM2): 4 bits in rank 1, 3 bits in rank 2, 1 otherwise (some embodiments mayallocate 4 bits per subband)

[0097] For Type I multi panel, an additional index i1,4 is available in X1, to select panel. Upto 16 bits may be needed in this case for 32 CSI-RS ports. If a 16-bit field is reserved for X1, it may be used both by the Type I single- and multi-panel codebooks if bit fields are allocated differently. However, some embodiments may allocate 24 bits in total to enable reusing fields from Type I Single Panel. As for the single panel case, the subband part X2 may either be encoded with 4 bits per subband for all configurations, or with different number of bits depending on codebook configuration.

[0098] For Type I Multi-Panel, one complication is that O-RAN Open Fronthaul normallyuses separate sets of layer endpoints for different antenna panels. In that case, the SE “PMI” may have to be sent to layer endpoints for each panel, together with information indicating a panel index (2 bits is enough for up to 4 panels). The U-Plane IQ samples are also sent to multiple layer endpoints. Declaring multiple panels as one single large array solves those issues, but it is not compliant with the Open Fronthaul Interface specification and may complicate other parts, e.g. sending of CSI-RS. The information about field sizes below is intended to illustrate differences between codebook types, and not to restrict the implementation in any way.● Wideband PMI (X1)– i1,1, i1,2, i1,3: 5 + 3 + 2 = 10 bits (some embodiments may use the same 16-bitallocation as for Type I single-panel, to simplify parsing) –i1,4: 2+2+2 = 6 bits (some embodiments may allocate 8 bits)● Per-subband PMI (X2, up to 18 subbands)– i2 (CM1): 2 bits in rank 1, 1 bit otherwise (some embodiments may allocate 2 bits)– i2,1, i2,2 , i2,3 (CM2): 2+1+1 = 4 bits in rank 1 and 1+1+1 = 3 bits otherwise (someembodiments may allocate 4 bits)

[0099] The Type II codebook was introduced in Release 15 of 5G NR and is quite differentfrom Type I in that it also provides amplitude information, in addition to the phase information in Type I codebooks. As an example, X1for 2 layers may need 4+11+3×2 +21×2=63 bits, which is much more than for Type I. Thus, some embodiments may use a dedicated set of information fields for Type II. Further variants of Type II are specified in newer 3GPP releases. The information about field sizes below is intended to illustrate differences between codebook types, and not to restrict the implementation in any way.● ^^ ∈ {1,2}: Rank● L: num beams, ^^ = 2 for PCSI-RS = 4, ^^ ∈ {2,3,4} if PCSI-RS > 4● NPSK: phaseAlphabetSize● ^^:(1) ^^ num elements of ^^1,4,^^ ^^ℎ^^^^^^ ^^^^,^^ > 0● K(2) є {4, 4, 6}subbandAmplitude = true● Wideband PMI (X1):– ^^1,1: ⌈^^^^^^2(^^1^^2)⌉ ≤ 4 bits– bits–bits– ^^1,4,^^: 3(2^^ − 1)^^ ≤ 21ν bits● Per-subband PMI (X2, up to 18 subbands)– if subbandAmplitude is false– ^^2,1,1: (^^1 − 1)^^^^^^2(^^^^^^^^) for rank 1 or 2– ^^2,1,2: (^^2 − 1)^^^^^^2(^^^^^^^^) for rank 2 only– if subbandAmplitude is true and for rank 1 or 2– ^^2,1,1: min(^^1,^^(2))^^^^^^2(^^^^^^^^)- ^^^^^^2(^^^^^^^^) + 2 (^^1 − min(^^1,^^(2)))–^^2,1,2: min(^^2,^^(2))^^^^^^2(^^^^^^^^)- ^^^^^^2(^^^^^^^^) + 2 (^^2 − min(^^2,^^(2)))II enhancedcodebook was introduced in 3GPP Release 16 and is described in 3GPP TS 38.214, clause 5.2.2.2.5. It is an improvement of the original Type II codebook from Release 15 and introducestap-domain compression of channel state information. Some parameter fields are the same as for the original Type II codebook, while other fields have been replaced by new fields. The information about field sizes below is intended to illustrate differences between codebook types, and not to restrict the implementation in any way.● ^^ ∈ {1,2,3,4}: rank● N3: number of subbands, ≤ 19 if R = 1, ≤ 37 if R = 2● ^^^^ = ⌈^^^^3^^^^⌉: number of tap-domain values (M{1,2}≤ 10, M{3,4} ≤ 5)● R:of PMI subbands per CQI subband● ^^ ∈ {2,4,6}: number of beams used to represent the channel per polarization● ^^^^^^ = ∑^^^^=1 ^^^^^^ ^^ ≤ 2^^0: number of non-zero coeffs● ^^0 = ≤ 60: max num. of non-zero coeffs per layer● Wideband PMI (X1):– ^^1,1: ⌈^^^^^^2(^^1^^2)⌉ = 4 bits– ^^1,2: ⌈log2 (^^1^^2^^)⌉ ≤ 13 bits in Release 16–18, 27 bits in Release 19–≤ 5 bits–rank 1-2, 12 bits / layer for rank 3-4● E.g. allocate 48 bits total (2×24 for rank 1-2, 4×12 otherwise)● ^^ ^^ − 1 ^3 ≤ 19: ⌈log 32 ( ^^1 − 1)⌉ ≤ 16, ⌈log ^3 − 12 ( ^^1 − 1)⌉ ≤ 12– for four–● Per-subband PMI (X2, up to 19 subbands if R = 1, up to 37 subbands if R = 2)– ^^2,3,^^: 4 bits per layer, total 16 bits– ^^2,4,^^: 3(^^ ^^^^ − 1) ≤ 357 bits– ^^^^ ≤ 476

[0101] include alternatives for mapping from CSI-RS ports to arrayantenna elements. The precoders defined by 3GPP have user data layers in downlink as inputs and CSI-RS ports as outputs. When the number of Tx array elements is larger than the number of CSI- RS ports, a mapping from CSI-RS ports to array elements is needed.

[0102] The CSI-RS ports can be viewed as a logical array (or multiple such arrays) where thenumber of ports equal ^^^^^^^^ = ^^^^^^1^^2^^^^. Here ^^^^ is the number of panels (1, 2, or 4 in 5G NRrelease 15), ^^1is the number of array columns, ^^2is the number of array rows, and ^^^^representsthe number of polarizations (the majority of 5G NR PMI codebooks today assumes ^^^^ = 2). Tosimplify the descriptions of the alternatives, it is assumed that a single antenna panel is used, ^^^^= 1, unless otherwise specified, but the embodiments and examples are not limited to a single panel.

[0103] Alternatives regarding how to map precoder output (CSI-RS ports) to antenna arrayelements include but are not limited to the ones in the list below, which are described further in the following subsections. When sending CSI-RS, the first two are possible in O-LLS today, but certain optimizations are possible, as described in the following. ^Full Tx array with pre-defined beam IDs for static or semi-static mapping^ Full Tx array with dynamically updated beam weights (WDBF)^ Full Tx array using hybrid beamforming approach^ Multiple small Tx arrays (one per CSI-RS port) and mapping, per polarization, from eachCSI-RS port to its corresponding Tx array ^One virtual array per supported CSI-RS array configuration and RU-internal mapping.

[0104] In general, the number of beam IDs to convey for a specific mapping equals thenumber of CSI-RS ports, i.e., ≤ 32 beam IDs. If the beam IDs have consecutive numbering, it is sufficient to send the first one. Otherwise, if numbers are not consecutive but the numbering step size is fixed, it is possible to include e.g., a step size to avoid the need to send all beam IDs.

[0105] An alternative method is to define a group of beam IDs and assign a beam groupidentifier, which may then be sent together with the PMI information, e.g., in SE “PMI”. Such grouping may be predefined by the O-RU, or via M-Plane. It may also be implemented, e.g., as a new ST4 command in C-Plane, where a list of beam IDs (optionally also with corresponding frequency-domain BFWs included) may be assigned a group ID. For frequency-domain BFWs, this may be referred to as, e.g., ‘fdBeamGrp’.

[0106] If CSI-RS ports are mapped to disjoint sets of Tx array elements, a single beam IDcorresponding to K BFWs is sufficient. However, additional explicit or implicit information is needed to describe which Tx array elements are connected to a specific CSI-RS port. This method may be used both to make a more efficient mapping from the logical array output of the precoder, but also to make transmission of CSI-RS more efficient (because a single BFW vector is sufficient). A further alternative is to have multiple beam IDs pointing to the same BFW vector in the O-RU. This will not reduce number of beam IDs but may reduce storage requirements.

[0107] Further, for cases where identical beamforming is used on each disjoint set of Tx arrayelements, it may be enough to send K / PCSI-RS BF weights in total. This is the case, e.g., for the multiple small Tx arrays described below.

[0108] In the following, some examples are given. They should not be considered as the onlypossibilities. Also, parts or all of some examples may be possible to combine to create new possibilities.

[0109] Some embodiments include full Tx array with pre-defined beam IDs for static or semi-static mapping. Here it is assumed that the full Tx array (for each panel) is exposed by the RU, or alternatively a single Tx array per polarization (and per panel). Each CSI-RS port has a separate beam ID for the mapping. The BFWs for each beam ID may be pre-defined by the RU vendor, or via M-Plane from the baseband unit and associated with beam IDs.

[0110] This type of mapping is supported in O-LLS already today. However, for pre-definedbeam IDs and current O-LLS protocol, the O-DU must be able to retrieve any pre-defined BFWs from the O-RU to be able to combine the precoder BFWs and mapping BFWs. This limitation does not apply to the embodiments described herein because it is then the O-RU that calculates BFWs from the RI / PMI information and may then combine these with its pre-defined mapping BFWs.

[0111] The maximum number of beam IDs needed may be calculated based on theconfigurations supported by the O-RU. Some configurations may be unsuitable depending on the O-RUs actual Tx array size, e.g., (N1, N2) = (3, 2) would not be suitable for a Tx array where the number of columns is not divisible by 3. As a worst case for 5G NR, if all possible CSI-RS configurations in Table 1 are supported, the following number of beam IDs are needed: ^5G NR Single panel: 1×2 + 1×4 + 2×8 + 2×12 + 2×16 + 3×24 + 3×32 = 246^ 5G NR Multi panel: 1×8 + 3×16 + 4×32 = 184

[0112] LTE supports even more configurations. Further, if e.g., a few pre-configured tilt / panoptions are desired, one may have to multiply the above with the number of tilt / pan steps.

[0113] When using beam ID based mapping today for, e.g., CSI-RS transmission, each CSI-RS port needs a dedicated beam ID. Thus, if such mapping is used in, or together with, SE “PMI”, a list of beam IDs is needed. The length of the list equals the number of CSI-RS ports.

[0114] Because each CSI-RS port typically maps only to a small subset of array elements,most of the BFWs stored will be zero, which could potentially be used by the RU vendor to compress data, e.g., by using a bitmask and only storing the non-zero subset. Such bitmask is not useful for other types of beamforming where all array elements have non-zero weight and will then increase storage needs. Therefore, it may be advantageous to define a specific range of beam IDs whose BFW vectors are known to be sparse and where a bitmask could be useful.

[0115] Instead of sending one beam ID per CSI-RS port, a reference to a list (e.g., a groupidentifier or the first beam ID in the list) of beam IDs may be defined and sent, e.g., in SE “PMI”, together with the information describing the PMI-based precoding.

[0116] Some embodiments include full Tx array with dynamically updated beam weights(WDBF). Here it is assumed that the full Tx array (for each panel) is exposed by the RU, or alternatively a single Tx array per polarization (and per panel) but BFWs are dynamically updatable by the O-DU instead of predefined. This may be the most flexible approach and the number of beam IDs required is lower than for the predefined approach because of the reuse possibility. Configurations from Table 1 that are not used in the same slot may share beam IDs because of the possibility of redefining them dynamically.

[0117] In O-LLS, the BF weights may be sent in C-Plane using existing section extensions,e.g., one BFW vector with SE 1 (beamforming weights), or one BFW vector per PRB bundle using SE 11 (flexible BF weights) or SE 19 (compact multiple port beamforming information). For this application, SE 19 may be the most suitable.

[0118] BFW vectors in O-LLS have equal number of (complex) values as the number of arrayelements, K. Only a subset of these might be needed when mapping a specific CSI-RS port. Including an antenna space bitmask, or e.g., Tx array row and column ranges, for each CSI-RS port may enable decreasing the amount of information to send because it is expected that most of the weights will have zero value.

[0119] If CSI-RS ports are mapped to disjoint sets of e.g., (M / N2)×(N / N1) Tx array elements,further optimization is possible. Instead of one bitmask vector per CSI-RS port, some embodiments may have one length K vector (or array) of indices where each index in the vector specifies the CSI-RS port that maps to the corresponding array element (out of the K elements). This will typically require less information than the bitmask approach. Further, with disjoint sets of Tx array elements, only one BFW vector (and one beam ID) may be needed (number of weights equals number of array elements K) and bit mask, row / column sizes or ranges, or a CSI-RS port index vector is used to select which weights that apply for a given CSI-RS port.

[0120] If the non-zero BWs for each such disjoint set are identical, but in different places inthe BFW vector (same beamforming applied to all CSI-RS ports), it is enough to send the non- zero BFWs for one of the mappings, together with explicit or implicit side information describing which CSI-port that maps to a certain disjoint set of Tx array elements.

[0121] When non-zero BFWs are independent between horizontal and vertical arraydimension. BFW vectors may be sent separately for horizontal and vertical dimension. These vectors can be seen as tensors and may be combined in the O-RU by using a Kronecker product.

[0122] Some embodiments include full Tx array using hybrid beamforming approach. Here itis assumed that the full Tx array (for each panel) is exposed by the RU but where the PMI-based precoder is seen as frequency-domain beamforming while the mapping from CSI-RS ports toantenna array elements is seen as time-domain beamforming (although may in some cases still be implemented by frequency-domain BF).

[0123] Thus, features in O-LLS intended for hybrid BF may be reused. O-RUs that supporthybrid BF may use existing methods for hybrid beamforming. With hybrid BF in O-LLS, there are K’ number of frequency-domain beamforming weights that can be applied within the array, where 0<K’≤K. Further, there is a mapping h(k) from array element k, 0≤k<K, to the frequency- domain BFW with index k’, 0≤k’<K’. If a desired PCSI-RS= K’, and if the mapping matches a valid (N1, N2) configuration for this PCSI-RS, then the hybrid BF method in O-LLS may be used, including, e.g., time-domain beam group in ST 4.

[0124] For O-RUs that only support frequency-domain BF (no hybrid BF), someembodiments may define a new similar 2-stage BF feature specifically for, e.g., CSI-RS transmission and PMI-based BF. This may be used by O-RUs implementing only frequency- domain BF, or combined with hybrid BF to create a 3-stage BF (precoding, mapping, and time- domain BF). Also, some embodiments may use the time-domain beam group in ST 4 (or similar functionality) to efficiently specify the mapping. However, such 2-stage or 3-stage BF may be complicated to combine with reciprocity-based BF in same slot as PMI-based BF.

[0125] Some embodiments include multiple small Tx arrays (one per CSI-RS port) andmapping from each CSI-RS port to its corresponding Tx array. Here, the O-RU exposes one (disjoint) (M / N2)×(N / N1) array per CSI-RS, i.e., M / N2 rows and N / N1 columns where all the small arrays share array elements with the full Tx array. Either the O-RU may expose one array per polarization or a dual-polarized array. In the latter case, two CSI-RS ports (one per polarization) map to the same small Tx array.

[0126] BF weights may be used for the mapping to array elements and because the arrays aresmall compared with the Tx array size, the number of BFWs is small. Further, the same BFW vector and same beam ID may be reused for each of the small Tx arrays. This may reduce amount of information to send in C-Plane and may be efficient when sending CSI-RS. However, mapping from RI / PMI precoder to the Tx array becomes slightly more complicated because a group of PCSI- RS endpoints must be specified in conjunction with SE “PMI”.

[0127] Instead of using BFWs, another alternative in this approach is to use attribute-basedBF (as in SE 2) where e.g., beamwidth and beam direction are specified in vertical and horizontal direction.

[0128] Yet another alternative is to use a tensor product approach (flexible), e.g., one tensorfor vertical BF and one for horizontal BF. The tensors may then be combined, by means of Kronecker products and may include, e.g., configurable phase slope along rows and columns for tilt and pan.

[0129] Some embodiments include one virtual array per supported CSI-RS arrayconfiguration and RU-internal mapping. In this alternative, the O-RU exposes one or more virtual arrays with dimensions according to supported (N1, N2) configurations from, e.g., 5G NR Type I single panel as shown in the left part of Table 1 or different number of CSI-RS ports (not necessarily for all possible PCSI-RS values). For example, the O-RU may provide a list of valid [N1, N2, Np] tuples. The O-DU may then select a preferred configuration from the list of supported configurations, based on, e.g., used number of CSI-RS ports, e.g., by providing an index into the list. Alternatively, multiple supported configurations are supported simultaneously, using different sets of endpoints. In any case, the O-RU internally handles the mapping from the exposed array to the physical array configuration. This may be an advantage, e.g., for non-rectangular arrays, and / or for arrays with irregular element spacing where it is difficult to use BFW-based mapping from CSI-RS ports to array elements.

[0130] The O-RU may support additional parameters via C-plane or M-plane to control e.g.,tilt, pan, cell shape, and / or tapering.

[0131] Some embodiments include channel quality information (CQI). CQI is described in3GPP TS 38.214, clause 5.2.2.1 and the minimum number of bits is listed in 3GPP TS 38.212. To convey the wideband part to the O-RU, at least the following number of bits is needed: ^CQI table indication: 2 bits (Release 18 has 4 CQI tables: Table 5.2.2.1-{2,3,4,5})^ Wideband CQI for the 1st transport block: 4 bits^ Wideband CQI for the 2nd transport block, if PCSI-RS > 4 and rank > 4: 4 bits

[0132] Additionally, there is a subband differential CQI value with 2 bits per CQI subband.

[0133] Some embodiments may include changes in multiple clauses of O-RAN WG4 CUS-plane specifications as well as corresponding M-plane specifications and YANG models from O- RAN WG4.

[0134] A new Section Extension, herein referred to as SE “PMI”, may be added in CUS-planespecifications to send RI / PMI information as well as necessary mapping from CSI-RS ports to Tx array elements. Support for the new SE may be indicated, e.g., per O-RU endpoint, via an added capability / feature in M-plane.

[0135] The following is one example specification modification, according to particularembodiments. ***************************************************************************** 7 C-PLANE PROTOCOL …7.2 Elementary procedures … 7.2.4 DL precoding configuration parameters and indications This clause addresses the method of specifying the precoding operation in the Category B O-RU. For Category A O-RU, if there is precoding in the DL processing chain, the precoding shall be implemented in the O-DU so the descriptions in this clause are not relevant. Annex I contains more information and examples regarding this precoding. Support for Transmit Diversity and Spatial Multiplexing with Large Delay CDD precoding schemes is optional for Category B O-RU. If O-RU does not support those precoding schemes, O-DU shall handle precoding of channels using those schemes on O-DU side as defined for Category A O-RU case. O-DU: 12 REs are generally sent on the interface from the O-DU to the O-RU but for certain IQ formats (selective RE sending as described in Annex A.6), fewer REs may be sent. In this case the missing REs would be considered by the O-RU to be equal to zero in both I and Q. For Single TX: For layer mapping at O-RU, complex-valued modulation symbols mapped in a sequence starting with d(q)(0),...,d( q )(Ms(yqm)b ^1 ) to frequency REs (k,l) and are packed into a PRB. A single ^For CRSCRS REs belong to a single Tx antenna and are mappedto frequency REs (k,l) for one layer and are packed into a PRB for transmission and are unpacked at O-RU (see Annex I for details). For Transmit Diversity: ^For layer mapping at O-RU, complex-valued modulation symbols mapped in a sequencestarting with d(q)(0),...,d( q )(Ms(yqm)b ^1 ) to frequency REs (k,l) and are packed into a PRB. A single eAxC is used for this purpose. ^For CRS mapping at O-RU, all CRS RE's are mapped to frequency REs (k,l) for alllayers and are packed into a PRB for transmission and are unpacked at O-RU (see Annex I for details). For Spatial Multiplexing with Large Delay CDD: ^At the O-DU, layer mapped symbols for each layer v, mapped in sequence starting withx(i) ^^x(0)(i) ... x( ^ ^1 ) T(i )^ to frequency REs (k,l) are packed into each PRB (see Annex I). ^For precoding atRU, different eAxCs are used for each layer.^ For CRS mapping at the O-RU, all CRS RE's for each layer are packed into a PRB fortransmission and are unpacked at the O-RU (see Annex I for details). ^All C-Plane message parameters are kept the same for precoding purposes.For other LTE precoding schemes and NR^ Precoding in the O-RU may be implemented in various ways that are vendor-defined andvendor-specific, especially for LTE TM7-TM10 and NR as there is no 3GPP-mandatedprecoding operation for these cases.O-RU: From the C-Plane precoding Section Extension, the O-RU determine the transmissionscheme using txScheme field. For Single TX: ^At the O-RU, input modulated symbols d(q)(0),...,d( q )(M (q)symb ^1 ) shall be unpacked and usedto perform layer mapping, precoding and antenna port mapping for single tx. ^For transmission on a single antenna port, a single layer shall be used, ^ ^ 1 , and themapping is defined as x(0)(i) ^d(0 )( i ) with ^^layer(symb = ^^sy0)mb. ^For single tx is defined byy( p)(i) ^x(0 )( i )p^ ^0, 4,5,7,8,11,13,107,108,109,110 ^ is the number of the singleantenna port used for transmission of the physical channel and i^0,1,..., M apsymb^ 1 ,Map mb ^layer sy Msymb.^For antenna port mapping p={0}, each y(i)=[y(p) (i) ]T RE shall go to antenna port y_p(i)after antenna port mapping. ^Since the PRB contains CRS sequences for one antenna port, the RE should extract theCRS RE's using crsSymbolNumber, crsReMask and crsShift (see Annex I for details) and are mapped to the appropriate RE position. For Transmit Diversity: ^At the O-RU, input modulated symbolsd(q)(0),...,d( q )(M(q)symb^1 )shall be unpacked and used to perform layer mapping, mapping. ^The appropriate precoder shall beof layers and antenna ports.^ For antenna port mapping p={0..N}, each y(i)=[y(p) (i) ]T RE shall go to each antennaport y_p(i) after antenna port mapping. ^Since the PRB contains CRS sequences for N antenna ports, the RE should extract theCRS RE's using crsSymbolNumber, crsReMask and crsShift (see Annex I for details) which are mapped to the appropriate RE position and rest of the REs are populated with zero data. For Spatial Multiplexing with Large Delay CDD: ^Input layer mapped symbols x(i)^ ^x(0)(i) ... x( ^ ^1 )(i )T^ shall be used to perform precodingat the O-RU based on numLayers, ^The O-RU shall change the precoderbased on the number ofantenna ports and number of layers. ^After precoding, for antenna port mapping p={0..N}, each y(i)=[y (p) (i) ]T RE shall go toeach antenna port y_p(i) after antenna port mapping. ^Since all PRBs contain CRS sequences for N antenna ports, then based on the layerID(layer 0) the O-RU shall extract CRS sequence using crsSymbolNumber, crsReMask andcrsShift (see Annex I) for CRS mapping to each of the antenna ports using the reMask bit field; the CRS REs from other layers can be ignored. For other LTE precoding schemes and NR ^One way to implement precoding in the O-RU is via the beamId values, wherein abeamId points to a beamforming vector that also implements the precoding operation. ^Another way to implement precoding in the O-RU is via CDBF where per-layercodebook information is associated with ueId and where beamId(s) are used for mapping from precoder output (CSI-RS ports) to antenna (tx-array elements), see clause 12.4.7. … 7.5 Coding of Section Type IEs … 7.5.3 Application layer, sections … Description: This parameter supports CIBF by providing a logical identifier for the set of channel information associated with a spatial stream of a UE sent via Section Type 6. This shall be used to support channel information sent from the O-DU to the O-RU. This is just a label and the specific value has no meaning regarding types of UEs that may be supported within the system. This parameter is also used within Section Type 5 to support CIBF, CDBF, and DMRS-BF, In the context of DMRS-BF, the format of the ueId field is specifically formatted to indicate a UE identifier and a layer number for the UE, see clause 12.6.1.3.1.2. Such formatting with UE identifier and UE layer number is also used for CDBF, see clause 12.7.2. If the O-RU reports the capability of 'non-scheduled-ueId-supported' = TRUE for an endpoint, and the O-DU configures 'non-scheduled-ueId-enabled' = TRUE the following O-RU interpretation shall apply: ^If the O-DU sets the ueId in the section header in ST 5 to 0x7FFF, the O-RU shallinterpret that the PRBs in the section description are not scheduled for the representative eAxC_ID (i.e. the eAxC_ID in the transport header). ^If the O-DU sets ueId to 0x7FFF in SE 10 with beamGroupType set to 10b when usedwith ST 5, the O-RU shall interpret that the PRBs in the section description are not scheduled for the specific eAxC_ID (refer to clause 7.9.13 for more details). In the context of use for CIBF, the value of ueId can be associated with at most one set of channel information (at a different time, the O-DU may associate the same ueId with another set of channel information). Mapping of ueId value to a set of channel information is global per O- RU.NOTE 1: While ueId is expected to take values in the full range 0x0000 to 0x7FFF, there is a limit on the number of valid ueId values an O-RU can support, which is dictated by O-RU advertised M-Plane parameter 'max-number-ues-15bit', which applies to CIBF. In the context of use for DMRS-BF, consult clause 12.6.1.3.1.2 regarding the persistence of the ueId value. In addition, the maximum number of UEs supported for the purposes of DMRS-BF is separately declared by the O-RU (called max-num-ues-supported, a per O-RU limit), and the value of ueId shall range from zero to the maximum number of UEs minus one, excluding the ueId bits dedicated to UE layers – this defines the "ueId space". If the maximum number of supported UEs declared by O-RU is larger than the maximum value which can be represented by the ueId bits dedicated to UEs, then the actual maximum number of UEs will equal to the maximum value determined by the ueId bits dedicated to UEs. NOTE 2: when the number of scheduled layers per UE is not a power of two, there will be unused ueId values within the total range. In the context of use for DMRS-BF, the possible number of layers to be scheduled per UE is governed by the O-RU-reported parameter ueid-max-layer-bits. Upon receiving this parameter from the O-RU, the O-DU shall configure ueid-layer-bits-configured which shall be less than or equal to ueid-max-layer-bits. The "ueId space" mentioned above is the product of max-num-ues- supported and 2 to the power of ueid-layer-bits-configured. The per-layer allocated bits (least- significant bits of ueId) shall count from zero to the number of layers minus one being scheduled for the UE. Example: If the maximum number of UEs for DMRS-BF were declared to be 10 (numbered from 0-9), and there are 3 bits configured for UE layers, then the permitted range of ueId (the "ueId" space) would be from 0 to 79 (from 0x00 to 0x4F). In the context of use for DMRS-BF, the O-RU shall report another limit, max-num-ueids, which governs the maximum number of unique ueId values within the "ueId space" that may be used by the O-DU(s). It is the responsibility of the O-DU to allocate the use of ueId values to fit within the limit of max-num-ueids, as well as fitting within the limit of max-num-ues-supported and ueid-layer-bits-configured. It would generally be true that max-num-ueids would be greater than max-num-ues-supported (to allow for multi-layer UEs), but whatever the reported and configured values, ueId use shall be governed by the most restrictive limit in place. In the context of use for CDBF, the ueId value is not persistent. The maximum number of layers to be scheduled per UE for CDBF is governed by the O-RU reported parameter ueid-max-layer-bits, which is part of CDBF capabilities and can have a different value than the corresponding parameter for DMRS-BF. Upon receiving this parameter from the O-RU, the O-DU shall configure ueid-layer-bits-configured to a value less than or equal to ueid-max-layer-bits. Value range: {000000000000000b-111111111111111b}. Type: unsigned integer. Field length: 15 bits. … 7.6 Section Extension elements 7.6.1 Overview Table 7.6.1 lists all the Section Extension parameters defined within the C-Plane: Table 7.6.1-1: Section Extension commands extType meaning extLen extension parameters octets meaning0 reserved 1 (1 reserved 1 for future use word) reserved 1 for future use 1 beamforming var bfwCompHdr 1 IqWidth(3:0) | compMeth(3:0) weights bfwCompParam 1 depends on compr. method bfwI (for TRX 0) var beamforming weight I value bfwQ (for TRX 0) var beamforming weight Q value … bfwI (for last TRX) var beamforming weight I value bfwQ (for last TRX) var beamforming weight Q value 2 beamforming var bfaCompHdr 2 BF attributes compr. header attributes bfAzPt var BF azimuth pointing param bfZePt var BF zenith pointing param bfAz3dd var BF azimuth beamwidth param bfZe3dd var BF zenith beamwidth param bfAzSl 3b BF azimuth sidelobe param bfZeSl 3b BF zenith sidelobe param 3 DL Precoding var codebookIndex 1 precoder codebook configuration (3 or 4 layerId 4b layer ID for DL Tx parameters and words) txScheme 4b transmission scheme indications numLayers 4b number of layers in DL Tx crsReMask 12b CRS RE Mask crsSymNum 4b CRS symbol number crsShift 1b CRS shift command beamIdAP1 15b Beam ID, Antenna Port 1 beamIdAP2 15b Beam ID, Antenna Port 2 beamIdAP3 15b Beam ID, Antenna Port 3 4 modulation compr. 1 (1 csf 1b constellation shift flag params word) modCompScaler 15b mod. compr. scale value 5 modulation var mcScaleReMask 12b Position of same scaling bits compression csf 1b constellation shift flag additional scaling mcScaleOffset 15b added mod. compr. scale values parameters 6 Non-contiguous 2 (2 repetition 1b repetition flag PRB allocation words) rbgSize 3b number of PRBs in the group rbgMask 28b mask of RBGs in the symbol(s) priority 2b priority of section description symbolMask 14b mask of symbols in the slot 7 Multiple-eAxC 1 eAxCmask 16b eAxC mask designation 8 regularization 1 regularizationFactor 16b regularization factor factor 9 Dynamic Spectrum 1 technology 1 interface name Sharing parametersextType meaning extLen extension parameters octets meaning10 Multiple ports var beamGroupType 2b type of beam grouping grouping numPortc 6b the number of ports beamId (or ueId) 15b beam ID (or UE ID) portListIndex 1 port-list index associated with each UE ID or beam ID11 Flexible BF weights var disableBFWs1b disable beamforming weights RAD 1b Reset After (PRB) Discontinuity bundleOffset 6b PRB bundle offset numBundPrb 1 Number of bundled PRBs bfwCompHdr 1 bitWidth(3:0) | compMeth(3:0) bfwCompParam for bundle 0 var depends on compr. method beamId (for PRB bundle 0) 2 Beam ID bfwI (for TRX 0, bundle 0) var BF weight I value for bundle 0 bfwQ (for TRX 0, bundle 0) var BF weight Q value for bundle 0 … … … bfwI (for last TRX, bundle 0) var BF weight I value for bundle 0 bfwQ (for last TRX bundle 0) var BF weight Q value for bundle 0 … … … bfwCompParam for last bundle var depends on compr. method beamId (for last PRB bundle) 2 Beam ID bfwI (for TRX 0, last bundle) var BF weight I value for last bundle bfwQ (for TRX 0, last bundle) var BF weight Q value for last bundle … … bfwI (for last TRX, last bundle) var BF weight I value for last bundle bfwQ (for last TRX & bundle) var BF weight Q value for last bundle 12 non-contiguous var priority, 2b priority of section description PRB allocation with symbolMask 14b mask of symbols in the slot frequency ranges offStartPrb(1) 8b offset to start of PRB range #1 numPrb(1) 8b number of PRBs in the range #1 … offStartPrb(R-1) 8b offset to start of PRB range numPrb(R-1) 8b number of PRBs in the range13 frequency hopping var nextSymbolId(1)4b start symbol of hop #1 nextStartPrbc (1) 10b start PRB for hop #1 … nextSymbolId (R-1), 4b start symbol of hop #R-1 nextStartPrbc (R-1) 10b start PRB for hop #R-1 14 Null-layer Info. for var nullLayerInd 1 Nulling-layer indication ueId-based beamforming 15 Mixed-numerology var frameStructure 1 FFT size, mu (SCS) Info. for ueId-based freqOffset 3 Frequency offset beamforming cpLength 2 Cyclic prefix length 16 Antenna mapping var antMask 8 Bitmask of Max.64 antenna for UE channel Info … based UL antMask var Bitmask of Max.64 antenna beamforming 17 User port group var numUeId 4b Number of ueIds per user indication 18 Uplink 2 (2 transmissionWindowOffset 16b transmission window offset Transmission words) transmissionWindowSize 14b transmission window size Management toT 2b type of transmissionextType meaning extLen extension parameters octets meaning19 Compact multiple var disableBFWs 1b disable BF weights port beamforming repetition 1b repetition flag information priority 2b priority of section description numPortc 6b num ports symbolMask 14b resource symbol bitmask bfwCompHdr 8b BF weight compression header … portReMask(for port 1) 12b RE bitmask for port 1 portSymbolMask(for port 1) 14b Symbol bitmask for port 1 bfwCompParam(for port 1) var BF weight compression parameter … for port 1 beamId(for port 1) 2 beam identifier for port 1 bfwI (for port 1 and TRX 0) var BF weight in-phase value for port 1 … TRX0 bfwQ (for port 1 and TRX 0) var BF weight quadrature-phase value … port 1 TRX0 portReMask(for last port) RE bitmask for last port portSymbolMask(for last port) Symbol bitmask last port bfwCompParam(for last port) BF weight compression parameter … for last port beamId(for last port) beamId for last port bfwI (for last port and TRX 0) BF weight in-phase value for last … port and TRX0 bfwQ (for last port and TRX 0) BF weight quadrature-phase value … last port TRX0 20 Dedicated var numPuncPatterns 8b number of puncturing patterns puncturing symbolMask(1) 14b first puncturing pattern symbol mask startPuncPrb(1) 10b first PRB to which puncturing … pattern applies numPuncPrb(1) 10b number of contiguous PRBs to … which first puncturing pattern … applies puncReMask(1) 12b first puncturing pattern RE mask rb(1) 1b first RB indicator rbgIncl(1) 1b first rbg included flag rbgSize(1) 3b first rbg size rbgMask(1) 28b first rbg bitmask symbolMask(last) 14b last puncturing pattern symbol mask startPuncPrb(last) 10b last PRB to which puncturing … pattern applies numPuncPrb(last) 10b number of contiguous PRBs to … which last puncturing pattern … applies puncReMask(last) 12b last puncturing pattern RE mask rb(last) 1b last RB indicator rbgIncl(last) 1b last rbg included flag rbgSize(last) 3b last rbg size rbgMask(last) 28b last rbg bitmask multiSDScope (1) … 1b first puncturing pattern ... multiSDScope (last) scope … last puncturing pattern scope 21 Variable PRB 1 (1 ciPrbGroupSize 1 channel information PRB group group size for word) size Channel prgSize 2b precoding resource block group Information size22 ACK / NACK request 1 (1ackNackReqId 2 used to identify the section word) description for which ACK / NACK feedback is requestedextType meaning extLen extension parameters octets meaning23 Multiple symbol var numSymPrbPa 4b number of symbol and resource modulation ttern block pattern compression 14b symbol mask par ameters sym t of par Mask symPrbPattern prbPattern 4b physical resource block pattern part of symPrbPattern numMcScaleOffset 4b number of modulation compression scaling value per symPrbPattern mcScaleReMask 12b modulation compression power scale RE mask csf 1b constellation shift flag prbMode 1b Bit flag to choose prbPattern mode or prb block mode prbBlkSize 1 PRB block size when prb block mode is used prbBlkOffset 1 PRB block offset when prb block mode is used 24 PUSCH DMRS var aIpnPerSym 1b allocated IPN per symbol configuration antDmrsSnr 1b antenna DMRS SNR userGroupSize 5b user group size userGroupId 8b user group identifier entryType 3b type of DMRS config entry dmrsPortNumber 5b DMRS port number (other parameters may be present depending on entryType) 25 Symbol reordering var txWinForOnAirSymbol0 4b transmission window for on-air for DMRS-BF symbol 0 … … … txWinForOnAirSymbol13 4b transmission window for on-air symbol 13 26 Frequency offset var numFoFb 7b number of frequency offset feedback 1stfreqOffsetFb 16b 1stUE frequency offset … var … last freqOffsetFb 16b the last UE frequency offset 27 O-DU controlled var beamType dimensionality 2b type of beam configuration reduction numElements 1stbeamId 6b Number of beamId values … 15b 1stbeamId value last beamId var … 15b the last beamId value ZZ Codebook-based var codebookTypeIndex 8b codebook type index beamforming spatialConfigIndex 5b spatial configuration index parameters rankInd 4b rank indication codebookIndex1 var wideband part of codebook subbandSize 8b subband size codebookIndex2 var subband part of codebook p2aMappingType 4b port-to-antenna mapping type beamId 15b beamId prbBlkSize 8b PRB block size29-127 reserved 1 (1reserved 1 for future use word) reserved 1 for future use <Add clause 7.7.ZZ and subclauses where ZZ is replaced with the first unused subclause of 7.7>7.7 Coding of Section Extension IEs … 7.7.ZZ SE ZZ: Codebook-based beamforming parameters Section Extension ZZ is used for CDBF, see clause 12.7, and applies to conveying information about downlink precoding based on feedback from a UE. It shall be used with ST 5. The O-DU conveys codebook information, which the O-RU uses to determine precoder weights with expansion to the number of CSI-RS ports, PCSI-RS, and mapping from CSI-RS ports to array elements (which can also involve expansion). The mapping to array elements can be done, e.g. by a list of consecutive beam IDs, one per CSI-RS port, where the first is given in the Section Extension. Table 7.7.ZZ.1-1 shows the overall structure of the Section Extension. The header includes parameters codebookType and spatialConfigIndex and is followed by a codebook description, which depends on codebookType, and finally there is the port-to-antenna mapping part. Both the codebook description and the port-to-antenna mapping can vary in size. Table 7.7.ZZ.1-2 shows an example for Type I Single-Panel with codebookMode = 1 where the port- to-antenna mapping is specified by a first beamId in a consecutive range of beamId, and where all PRBs use same port-to-antenna mapping. The O-RU shall interpret the ueid-layer-bits-configured least significant bits of ueId as layer index of a UE, while remaining most significant bits of ueId are used to enumerate UEs. If supported by the O-RU, SE 10 may be used by the O-DU in combination with SE ZZ to group endpoints with corresponding ueIds for multiple UE data layers. When SE 10 is not used, a separate ST 5 + SE ZZ is sent to the endpoint of each scheduled data layer of a UE, where typically only the LSBs of ueId differs for the different layers of a UE, while the codebook description and port-to-antenna mapping may be identical. Table 7.7.ZZ.1-1: Section Extension ZZ to convey information for codebook-based DL BF 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes ef extType = ZZ 1 NextLen[7:0] 1 N+1codebookTypeIndex[7:0] 1 N+2 reserved spatialConfigIndex[4:0] 1 N+3 codebook description var N+4port-to-antenna mapping var varZero-pad to ensure 4-byte boundary varTable 7.7.ZZ.1-2: Section Extension ZZ example for TYPE-1-SINGLE-PANEL-CBMODE-1 codebook, p2aMappingType = 0001b (first beamId in a range), and prbBlkSize = 0 (all PRBs use same mapping) 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes ef extType = ZZ 1 NextLen[7:0] 1 N+1codebookTypeIndex[7:0] = 0x01 1 N+2reserved spatialConfigIndex[4:0] 1 N+3reserved rankInd[3:0] 1 N+4 reserved 1 N+5codebookIndex1[15:0] 2 N+6subbandSize[7:0] 1 N+8codebookIndex2 var N+9reserved p2aMappingType[3:0] = 0001b 1 varprbBlkSize[7:0] = 0 1 reserved 1st beamId[14:8] 11st beamId[7:0] 1zero-pad to ensure 4-byte boundary varThe codebook description part of SE ZZ contains information to describe the codebook selected by codebookType in the header and can vary in size. Table 7.7.ZZ.2-1 shows the codebook description for codebook type TYPE-1-SINGLE-PANEL-CBMODE-1. Different codebook types are used depending on the value of 3GPP parameter ‘codebookMode’. Table 7.7.ZZ.2-1: Codebook description for codebook types TYPE-1-SINGLE-PANEL- CBMODE-1 and TYPE-1-SINGLE-PANEL-CBMODE-2 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes reserved rankInd[3:0] 1 N+4 reserved 1 N+5 codebookIndex1[15:0] 2 N+6subbandSize[7:0] 1 N+8codebookIndex2 var N+9The port-to-antenna mapping part of SE ZZ contains information to describe the mapping between CSI-RS ports and antenna (tx-array elements). Different examples and options depending on parameter p2aMappingType and prbBlkSize are shown in Table 7.7.ZZ.3-1 to 7.7.ZZ.3-5.Table 7.7.ZZ.3-1: Port-to-antenna mapping for p2aMappingType = 0000b including an explicit list of beamId values (one beamId per CSI-RS port) 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes reserved p2aMappingType[3:0]=0000b 1 varreserved 1reserved 1st beamId[14:8] 11st beamId[7:0] 1… var reserved Last beamId[14:8] 1 Last beamId[7:0] 1Table 7.7.ZZ.3-2: Port-to-antenna mapping for p2aMappingType = 0001b including the first beamId in a consecutive range of beamId values and where same mapping is applied to all PRBs 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes reserved p2aMappingType[3:0]=0001b 1 var1st block prbBlkSize[7:0] = 0 1reserved 1stbeamId[14:8] 1 1stbeamId[7:0] 1 Table 7.7.ZZ.3-3: Port-to-antenna mapping for p2aMappingType = 0001b where different “first beamId” in a consecutive range is specified for different PRB ranges 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes reserved p2aMappingType[3:0]=0001b 1 var1st block prbBlkSize[7:0] 1reserved 1st block 1st beamId[14:8] 11stblock 1stbeamId[7:0] 1 2ndblock prbBlkSize[7:0] 1 reserved 2nd block 1st beamId[14:8] 12ndblock 1stbeamId[7:0] 1 …varnth block prbBlkSize[7:0] 1reserved nthblock 1stbeamId[14:8] 1 nth block 1st beamId[7:0] 1Table 7.7.ZZ.3-4: Port-to-antenna mapping for p2aMappingType = 0010b where a single beamId is shared among all CSI-RS ports, using implicit antenna masks, and where same mapping is applied to all PRBs 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes reserved p2aMappingType[3:0]=0010b 11st block prbBlkSize[7:0] = 0 1reserved beamId[14:8] 1 beamId[7:0] 1Table 7.7.ZZ.3-5: Port-to-antenna mapping for p2aMappingType = 0010b where a single beamId per PRB block is shared among all CSI-RS ports, using implicit antenna masks 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes reserved p2aMappingType[3:0]=0010b 11st block prbBlkSize[7:0] 1reserved 1st block beamId[14:8] 11st block beamId[7:0] 12ndblock prbBlkSize[7:0] 1 reserved 2ndblock beamId[14:8] 1 2nd block beamId[7:0] 1… varnth block prbBlkSize[7:0] 1reserved nth block beamId[14:8] 1nthblock beamId[7:0] 1 Section Extension ZZ is specific for codebook-based dynamic beamforming and can only be used with a subset of Section Extensions allowed in Section Type 5 messages. In the present document, use of SE ZZ with any of Section Extensions 1–3, 7–9, 11, 14–19, 21, and 24–27 is not specified. Specified usage of Section Extensions together with SE ZZ are as follows: ^Section Extension 10 (optional) may be used together with SE ZZ in order to group UElayers, allowing a single SE ZZ to be sent per UE even for rank greater than one. If SE 10 is not used, a separate SE ZZ shall be sent per scheduled UE layer. ^Section Extensions 4, 5, 6, 12, 13, 20, 22 and 23 can also be used.Description: This parameter selects codebook type and related parameters as an index into the O- DU configured M-Plane list cdbf-codebook-types-used. See also clause 12.7.2 Value range: {0x01 – 0xFF} Value 0x00 is reserved. Type: unsigned integer Field length: 8 bits Description: This parameter represents the rank indication (RI) for the codebook, which can be reported by the UE as part of CSI reporting. Together with PMI, it used to determine a specific codebook, e.g., as described in TS 38.214, clause 5.2.2.2. The maximum codebook rank is 8 but parameter rankInd supports rank up to 16 to have some room for future codebooks supporting higher rank. Value range: {0000b–1111b: corresponding to 1–16 layers}. Type: unsigned integer Field length: 4 bitsDescription: This parameter contains codebook indices for the wideband part of the codebook, e.g. i1indices in Precoding Matrix Indicator (PMI) as described in 3GPP TS 38.214 clause 5.2.2.2. Some field sizes are larger than the bit-widths currently required for Type I Single-Panel codebooks as specified in TS 38.214, clause 5.2.2.2.1 (up to 32 CSI-RS ports), to have some headroom for increased number of CSI-RS ports in future 3GPP releases. Indices shall always occupy the least significant bits of respective fields, i.e., if the bit-width of a particular index is smaller than the field size of codebookIndex1, there will be unused MSBs, which shall be set to zero. Value range: As defined in Table 7.7.ZZ.7-1 for Type I single-panel codebooks as specified in TS 38.214. NOTE: Future support for other codebook types, e.g.3GPP Type II variants, can require different bit allocation and field length for codebookIndex1. Table 7.7.ZZ.7-1: Bit allocation of codebookIndex1 for codebook-types NR_TYPE_1_SINGLE_PANEL_CBMODE_1 and NR_TYPE_1_SINGLE_PANEL_CBMODE_2 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes reserved i1,3[2:0] i1,2[4:0] 1 1i1,1[7:0] 1 2Type: unsigned integer (concatenated bit fields) Field length: variable Description: This parameter describes the subband size in number of PRBs. Together with information about number of PRBs in the section description, it can be used to calculate number of subbands. Value range: {0x01 – 0xFF: subband size in number of PRBs, 0x00 is a special value indicating wideband, i.e. all PRBs belong to a single subband}. Type: unsigned integer Field length: 8 bits Description: This parameter contains codebook indices for the per-subband part of the codebook (i2 indices in 3GPP PMI). The field size depends on chosen codebookType. Value range: As defined in Table 7.7.ZZ.9-1 and Table 7.7.ZZ.9-2 depending on codebookType.Table 7.7.ZZ.9-1: Bit allocation of codebookIndex2 for codebook-type NR_TYPE_1_SINGLE_PANEL_CBMODE_1 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes 1st subband i2 2nd subband i2 ··· 1 N+1… var varLast subband i2 if var var numSubbands is divisible by 4, zeros otherwise Table 7.7.ZZ.9-2: Bit allocation of codebookIndex2 for codebook-type NR_TYPE_1_SINGLE_PANEL_CBMODE_2 0 (msb) 1 2 3 4 5 6 7(lsb) # of Octet bytes 1stsubband i2 2ndsubband i2 if numSubbands is greater 1 N+1 than one, zeros otherwise … var var second-to-last subband i2 if numSubbands is last subband i2 if numSubbands is even, var var even, last subband otherwise zeros otherwise Type: unsigned integer (concatenated bit fields) Field length: variable Description: This parameter describes the mode of mapping from CSI-RS ports (as output from codebook precoding), to antenna (tx-array) elements. The number of CSI-RS ports can be determined from the M-plane configuration of CSI-RS ports referred to by spatialConfigIndex. For more information regarding p2aMapping, see clause 12.7.4. Value range: { 0000b: A list with one beamId per CSI-RS port is included. All PRBs in the Section Description use same beamIds. 0001b: The first beamId in a range of consecutive beamIds (one per CSI-RS port) is included. Different PRB ranges may have different “first beamId” if the O-RU declares max-prb- blks-per-sec-ext-ZZ > 1. 0010b: A single beamId is included, where each CSI-RS port uses a disjoint set of weights from the beamforming weight vector pointed to by the beamId. Different PRB ranges may have different “first beamId” if the O-RU declares max-prb-blks-per-sec-ext-ZZ > 1. 0011b–1111b: reserved}. Type: unsigned integer Field length: 4 bits Description: This parameter describes the CSI-RS port configuration as an index into an M-plane defined list cdbf-spatial-configs-used, see clause 12.7.2.Value range: {00001b–11111b}, value 00000b is reserved. Type: unsigned integer Field length: 5 bits Description: This parameter describes a beamId used for mapping from CSI-RS port to antenna (tx-array elements) when CDBF is used. Depending on value of p2aMappingType, it could be a list of PCSI-RSbeamIds (where PCSI-RSis the number of CSI-RS ports), the first beamID in a list of PCSI-RS consecutive beam IDs starting with beamId, or a single beam ID, see clause 12.7.4. The beamId defines the beam pattern (including any port expansion from CSI-RS port to antenna) to be applied to an output port of codebook precoding of user layers in the O-RU, instead of directly on user layer data as for WDBF beamId. Apart from that, this beamId behaves like normal beamId as described in clause 7.5.3.9 and shares same value space. Value range: {0x0001–0x7FFF; 0x0000 means no BF to be done, i.e. all weights are equal to one}. Type: unsigned integer. Field length: 15 bits. Description: This parameter is applicable for p2aMappingType 0001b and 0010b. The parameter is used to indicate the size of a contiguous PRB block for which a specific beamId is valid. The first block starts at PRB startPrbc and ends at PRB startPrbc + 1stprbBlkSize - 1. The sum of all prbBlkSize fields in the port-to-antenna mapping shall equal the number of PRBs referred by the section description. Value range: {0x01 – 0xFF}. Value 0x00 is a special value that indicates all remaining PRBs. Type: unsigned integer. Field length: 8 bits. 10.2 Mandatory and optional capabilities This clause provides details regarding which capabilities within the present document are mandatory and which are optional. The capability requirements of O-DU can be different from the O-RU because in many cases, the O-DU needs to implement multiple options as mandatory to ensure interoperability with O-RUs that have optional capabilities. For example, the ability to support many compression methods may be mandatory in the O-DU while in O-RUs there may be only a single mandatory compression method to allow simplicity in O-RU design (while vendors may enhance their O-RU product offering by implementing some of the optional compression methods).Table 10.2 describes the capabilities required of O-DU and O-RU units. There are three choices: Mandatory: The unit shall support the described capability to be O-RAN compliant. Conditional Mandatory: The unit shall support the described capability to be O-RAN compliant, but the additional information column describes the conditions under which the capability is mandatory. Optional: The unit need not support the capability and still be O-RAN compliant, but if the unit does support the described capability it shall support it in the way described within the present document. Table 10.2-1: O-RAN mandatory and optional features O-DU O-RU Category Featuresupportsupport Additional informationSupport for Category-A O-RU (up to Mandatory N / A The O-DU may only support fewer 8 spatial streams) than 8 spatial streams; that number of spatial streams shall however be supported for Category-A O-RUs. O-RU Support for Category-A O-RU (> 8 Optional N / A Category spatial streams) Support Support for Category-B O-RU Mandatory N / A (precoding in O-RU) IEEE 802.1X supplicant functionality Optional Mandatory Grand Master Clock Redundancy Optional Optional Principles for Grand Master Clock Security redundancy are provided in Annex P.2.3.1 of IEEE 1588. Guidelines are provided in Annex G of O-RAN Synchronization Architecture and Solution Specification. Beam index based (PDBF) Mandatory Conditional Condition applies to UE-specific BF Mandatory for any O-RU capable of BF; a non- BF O-RU shall be supplied a zero beamId if a C-Plane message containing a beamId is sent at all. Real-time BF Weights (WDBF) Conditional Conditional Condition for O-DU: Mandatory only Mandatory Mandatory for O-DUs designed to support any kind of BF that involves the operation of updating BF weights in real-time, these kinds include CIBF and DMRS-BF Condition for O-RU: mandatory for any O-RU internally calculating BF weights, these kinds include CIBF Beam- and DMRS-BF. forming Real-time beamforming attributes Optional Optional This is considered to not internally (ABBF) use BF weights. Real-time UE channel Info (CIBF) Optional Optional This is considered to internally use BF weights. Predefined beam tilt for beam index Optional Optional based beamforming Antenna calibration support Optional Optional Null-layer Info. for ueId-based Optional Optional beamforming using Section Extension 14 User port group indication for Optional Optional beamforming based on UE channel (Section Extension 17) Multiple beamId tables Optional Optional See clause 7.5.3.9 and 12.4.1O-DU O-RU Category Featuresupportsupport Additional informationDMRS-based BF (DMRS-BF) Optional Optional DMRS-based BF with equalization Conditional Optional Condition for O-DU: If DMRS-BF is (DMRS-BF-EQ) Mandatory supported DMRS-based BF without Conditional Optional Condition for O-DU: If DMRS-BF is equalization (DMRS-BF-NEQ) Mandatory supported DMRS processing including Mandatory Conditional Condition for O-RU: DMRS-BF-EQ equalization functionality Mandatory is supported. See clauses 12.6.1.1 and 12.6.3.1 for equalization use details in the O- RU and O-DU. Codebook-based dynamic Optional Optional This is considered to internally use beamforming (CDBF) BF weights Relevant to DMRS-BF, conveyance Conditional Conditional Condition for O-DU: DMRS-BF is of port-reduced DMRS data from O- Mandatory Mandatory supported. RU to O-DU Condition for O-RU: DMRS-BF is supported. IQ Data Formats Fixed point (no compression) Conditional Conditional 16-bit mandatory (others optional) Mandatory Mandatory Condition for O-RU and O-DU: applicable when DMRS-BF is not used. Fixed point (no compression) Optional Optional 16-bit mandatory if this data format For UL SINR data transmission is supported (other bit widths optional). Block floating point compression Conditional Conditional 9, 12 & 14-bit mantissa mandatory if when not using DMRS-BF Mandatory Mandatory this compression method is supported (others optional). Condition: if an O-DU or O-RU supports any IQ compression it shall support this one. Block floating point compression, for Conditional Conditional 8, 9-bit mantissa mandatory (others use of DMRS-BF-EQ Mandatory Mandatory optional) Condition for O-RU: endpoints using DMRS-BF-EQ Condition for O-DU: O-DU using DMRS-BF-EQ Block floating point compression, for Conditional Conditional 9-bit mantissa mandatory (others use of DMRS-BF-NEQ Mandatory Mandatory optional) Condition for O-RU: endpoints using Bandwidth DMRS-BF-NEQ Saving Condition for O-DU: O-DU using DMRS-BF-NEQ Block floating point compression, for Mandatory Mandatory 8-bit mantissa mandatory (others UL SINR data transmission optional) Block scaling compression Optional Optional 9 & 14-bit scaler mandatory if this compression method is supported (others optional). ^-law compressionOptional Optional 9 & 14-bit width mandatory if this compression method is supported (others optional). Modulation compression Optional Optional 4-bit width mandatory if this compression method is supported (others optional). Block floating point compression + Optional Optional 9, 12 & 14-bit mantissa mandatory if selective RE sending this compression method is supported (others optional). Modulation compression + selective Optional Optional 4-bit width mandatory if this RE sending compression method is supported (others optional). Block floating point compression + Optional Optional 9, 12 & 14-bit mantissa mandatory if selective RE sending with this compression method is sReSMask1 and sReSMask2 in U- supported (others optional). Plane section headerO-DU O-RU Category Featuresupportsupport Additional informationModulation compression + selective Optional Optional 4-bit width mandatory if this RE sending with sReSMask1 and compression method is supported sReSMask2 in U-Plane section (others optional). header Presence of udCompLen Conditional Optional If the O-RU declares support of Mandatory udCompLen then it shall be used, otherwise it shall be omitted (in DL and UL U-Plane messages); this is only relevant for block floating point with selective RE sending or modulation compression, with selective RE sending. Real-time variable bit-width Optional Optional IQ data format is determined by value of udCompHdr. This implies presence of udCompHdr in U-Plane messages. Real-time variable bit-width per Optional Optional IQ data format is determined by Channel (per data section) value of udCompHdr. This implies presence of udCompHdr in U-Plane messages. Values of udCompHdr can be different in different sections in the U-Plane messages. Static configuration of U-Plane IQ Conditional Conditional IQ data format is determined by M- format and compression header Mandatory Mandatory Plane configuration. This implies absence of udCompHdr in U-Plane messages. Mandatory for supported IQ formats listed in first 7 rows under "IQ Data Formats" in this table. Beamspace compression Optional Optional This compression algorithm is specific to beamforming weights. Channel information compression Optional Optional ^ No compression / Fixed Conditional Conditional 16-bit width for ciIsample and point Mandatory Mandatory ciQsample mandatory if the channel information based BF feature is supported (other bitwidth optional). ^Block Floating PointOptional Optional^ Block Scaling Optional Optional ^^-law Optional OptionalUse of "symInc" flag to allow Optional Optional multiple symbols in a C-Plane section Coupling via sectionId Value Mandatory MandatoryCoupling via Frequency and Time Conditional Conditional If O-RU or O-DU supports "Coupling Mandatory Mandatory via Frequency and Time with Priorities" it shall also support this one. Coupling via Frequency and Time Optional Optional with Priorities Coupling via Frequency and Time Optional Optional Refer to clause 7.8.1.5 and clause with Priorities (Optimized) 7.9.8 PRACH data transfer without C- Optional Optional Plane SRS data transfer without C-Plane Optional Optional Transmission blanking Optional Optional Defined-duration sleep Optional Optional Separately for TRX_CONTROL and ASM, see clause 16.4 Energy Undefined-duration sleep Optional Optional Separately for TRX_CONTROL and Savings ASM, see clause 16.5 Sleep extension Optional Optional Separately for TRX_CONTROL and ASM; only applies if defined- duration sleep is supported, see clause 16.9O-DU O-RU Category Featuresupportsupport Additional informationSleep modes Optional Optional Any of the four possible sleep modes may be supported, separately for TRX_CONTROL and ASM; see clause 16.1 Section Type 8 "ready" message Optional Optional Only applies if Section Type 8 is (see 16.6.2) supported, see clause 7.5.3.56 and 16.6.2 M-Plane emergency wake-up Optional Optional See clause 16.12 Defined Transport Method Mandatory Mandatory Measured Transport Method Optional Optional If O-RU supports Measured (eCPRI Msg 5) Transport Method it shall support both 1-Step and 2-step version of T12 measurement and at least one of 1-Step or 2-Step version of T34 measurement. If the O-DU supports T34 O-DU - measurement it shall support both O-RU Timing 1-Step and 2-Step version. See clause 4.4.4.4 for more detailed information. External Antenna Delay handling Optional Optional Using Tda and Tau parameters as using Minimal O-DU Impact Method defined in clause 4.7.2. Beamforming delay profile Conditional Conditional M-Plane feature BF-DELAY- Mandatory Mandatory PROFILE Condition for O-DU and O-RU: support for DMRS-BF. G.8275.1 Conditional Conditional When the G.8275.1 profile is used: Mandatory Mandatory In LLS-C1 / C2 / C3, the O-RU shall be synchronized from a PTP source using this profile and may optionally use PLFS assistance as well In LLS-C1 / C2 / C3 / C4, the O-DU may optionally be synchronized from a PTP source using this profile and may optionally use PLFS assistance as well. In LLS-C1, the O-DU shall synchronize the O-RU using this PTP profile on the fronthaul interface. The O-DU shall synchronize the O-RU using PLFS as well only if the O-RU requires it (otherwise it is optional). Synchroni- In LLS-C2, the O-DU shall zation synchronize the fronthaul network elements using this PTP profile and PLFS on the fronthaul interface. In LLS-C3 / C4, the O-DU does not transmit synchronization signals to the O-RU. In LLS-C2 and LLS-C3 topologies supporting Shared cell, the network elements in the Fronthaul synchronization chain (FHM or cascaded O-Rus) that are on the path to other network elements in the synchronization chain shall synchronize them using this PTP profile and PLFS on the fronthaul interface. G.8275.2 Optional Optional When the G.8275.2 profile is used:O-DU O-RU Category Featuresupportsupport Additional informationO-DU (in LLS-C1 / C2 / C3 / C4) or O- RU (in LLS-C1 / C2 / C3) may optionally be synchronized from a PTP source using this PTP profile. In LLS-C1 / C2, O-DU may optionally synchronize the O-RU using this PTP profile on the fronthaul interface. Local PRTC Optional Optional O-DU (in LLS-C1 / C2 / C3 / C4) or O- RU (in LLS-C4) may optionally be synchronized from a local time source, for example GNSS-based. L2: Ethernet Mandatory Mandatory L3: IPv4, IPv6 (CUS Plane) Optional Optional QoS over Fronthaul Mandatory Mandatory Prioritization of different U-Plane Optional Optional traffic types Transport Support of Jumbo Ethernet frames Optional Optional Features eCPRI Mandatory Mandatory support of eCPRI concatenation Optional Optional IEEE 1914.3 transport header Optional Optional See clause 5.1.3.3. Application layer fragmentation Mandatory Mandatory C-Plane and U-Plane. Radio Transport layer fragmentation Optional Optional U-Plane (see clause 5.1.3.2.8). Section Type 0 Optional Mandatory O-RU may ignore message if blanking or other Section Type 0 utility is not supported. Section Type 1 Mandatory Mandatory Section Type 3 Mandatory Mandatory Section Type 4 Optional Optional Specific for slot-level configuration control Section Type 5 Conditional Conditional Condition: mandatory if O-RU or O- Mandatory Mandatory DU supports CIBF and / or DMRS- BF. Section Type 6 Conditional Conditional Condition: mandatory if O-RU or O- Mandatory Mandatory DU supports CIBF. Section Type 7 Conditional Conditional Condition: mandatory if O-RU or O- Mandatory Mandatory DU supports LAA. Conditional Conditional Condition: Mandatory if SE 22 for Mandatory Mandatory ACK / NACK request is supported. Section Specific to ACK / NACK reporting for Types and Section Type 8 section descriptions in C-Plane Section messages Extensions Section Type 9 Optional Conditional Condition for O-RU: mandatory if Mandatory DMRS-BF-EQ is supported Section Type 10 Conditional Conditional Condition for O-DU: DMRS-BF is Mandatory Mandatory supported (EQ and NEQ) Condition for O-RU: DMRS-BF-EQ is supported, or when DMRS-BF- NEQ is supported and the O-RU could alter the time or frequency offset of a UE-layer Section Type 11 Optional Conditional Condition for O-RU: DMRS-BF-EQ Mandatory is supported Beamforming weight transfer using Conditional Conditional Condition for O-DU: Mandatory only Section Extension 1 Mandatory Mandatory for O-DUs designed to support any kind of BF that involves the operation of updating BF weights in real-time;O-DU O-RUCategory Featuresupportsupport Additional informationCondition for O-RU: for any O-RU internally using BF weights, the ability to update the weights in real- time via C-Plane messages (using "Real-time BF Weights") shall be mandatory. Beamforming attribute transfer Optional Optional Attribute-based beamforming is using Section Extension 2 optional. DL precoding configuration using Optional Optional While Category B is mandatory, it is Section Extension 3 possible to precode using beamforming so use of this extension is optional. ^ First Data Layer and Non- Conditional Conditional Condition: DL precoding first data layer association Mandatory Mandatory configuration using Section Extension 3 is supported by O-DU and O-RU. Modulation compr. Parameters Conditional Conditional Condition for O-DU: If modulation using Section Extension 4 Mandatory Mandatory compression is supported then it is mandatory for O-DU to support Section Extension 4 Condition for O-RU: If modulation compression is supported and the O-RU does not support Section Extension 5 then it is mandatory for O-RU to support Section Extension 4 Modulation compr. Parameters Conditional Conditional Condition for O-DU: If modulation using Section Extension 5 Mandatory Mandatory compression is supported then it is mandatory for O-DU to support Section Extension 5 Condition for O-RU: If modulation compression is supported and the O-RU does not support Section Extension 4 then it is mandatory for O-RU to support Section Extension 5 Non-contiguous PRB allocation Optional Optional Use of non-contiguous PRBs is using Section Extension 6 optional. eAxC masking using Section Optional Optional Use of eAxC masking is optional. Extension 7 Provide MMSE parameters using Conditional Conditional Specific to Channel-Info Section Extension 8 Mandatory Mandatory beamforming; O-DU condition: if O-RU and O-DU both support Channel-Info BF, then the O-DU shall use Section Extension 8 to convey MMSE parameters; O-RU condition: if the O-RU supports Channel-Info BF, then the O-RU shall accept Section Extension 8 MMSE parameters from the O-DU. LTE / NR DSS using Section Optional Optional DSS using overlapping carriers is Extension 9 possible; DSS using this Section Extension is optional. Group configuring of multiple ports Optional Optional Use of multiple port (multiple eAxC) using Section Extension 10 grouping is optional. Support 'USER-GROUP- Optional Optional Send all layer information for UEs OPTIMIZATION' with Section belonging to a user group using Extension 10 single description Support of beamGroupType = 10b Optional Conditional Condition for O-RU: mandatory if and 11b with SE 10 Mandatory DMRS-BF is supported. Flexible Beamforming Weights Optional Optional Use of flexible beamforming weights using Section Extension 11 Section Extension is optional. contInd flag in SE 11 Optional Optional See clause 7.7.11.9O-DU O-RUCategory Featuresupportsupport Additional informationbundleOffset in SE 11 Optional Optional See clause 7.7.11.10 Non-contiguous PRB allocation with Optional Optional frequency ranges using Section Extension 12 PRB allocation with frequency Optional Optional hopping using Section Extension 13 Nulling-layer Info. for ueId-based Optional Optional beamforming using Section Extension 14 Mixed-numerology Info. for ueId- Optional Optional based beamforming using Section Extension 15 Antenna mapping in UE channel Optional Optional Use of antenna mapping in UE information based UL beamforming channel information based UL using Section Extension 16 beamforming is optional. Indication of user port group using Optional Optional Section Extension 17 Uplink traffic management using Conditional Conditional Mandatory if uplink traffic Section Extension 18 Mandatory Mandatory management using C-Plane is supported. Not permitted if uplink traffic management using C-Plane is not supported. Compact beamforming information Optional Optional See clause 7.7.19 and 7.9.11. for multiple port using Section Extension 19 Dedicated puncturing Section using Optional Optional See clause 7.7.20 and 7.9.12. Extension 20 Variable PRB group size for Optional Optional Channel Information using Section Extension 21 Sending PRG size using Section Optional Optional See clause 7.7.21.1 and 7.7.21.3 Extension 21 with Section Type 6 Sending PRG size using Section Optional Optional See clause 7.7.21.1 and 7.7.21.3 Extension 21 with Section Type 5 ACK / NACK request using Section Optional Optional See clause 7.7.22 and 7.2.8 for Extension 22 more details. Multiple symbol mcScaleOffset See clause 7.7.23 using Section Extension=23. Optional Conditional Condition for O-RU: Mandatory if (PRB-MASK mode) Mandatory both CDBF and Modulation Compression are supported The default mode is PRB-MASK mode. O-RU can indicate support for PRB-BLOCK mode of Section PRB-BLOCK mode of Section Conditio Extension 23 using M-Plane Extension 23 Optional nal Mandatory advertised capability. Refer to clause 7.7.23.1 for more details. Condition for O-RU: Mandatory if both CDBF and Modulation Compression are supported SE 24 PUSCH DMRS Configuration Conditional Conditional Condition: mandatory if DMRS-BF is Mandatory Mandatory supported SE 25 symbol reordering pattern Optional Optional SE 26 frequency offset reporting Optional Optional O-DU controlled dimensionality Optional Optional See clause 7.7.27.1 reduction for DMRS-based beamforming using Section Extension 27 Conveying codebook description Conditional Conditional Condition: mandatory if CDBF is and port-to-antenna mapping for Mandatory Mandatory supported CDBF using Section Extension ZZ12.4 beamId use for various beamforming methods 12.4.1 Overview There are two main domains in which beamforming is executed, frequency-domain and time- domain; it is also possible to combine both (called “hybrid beamforming”). Frequency-domain beamforming is done between the RE mapping and FFT / iFFT processing stages (in UL and DL respectively) so is inherently a digital operation. Time-domain beamforming may be executed digitally or in the analog domain. A characteristic of frequency-domain beamforming when used with OFDM is that different users may use the same time slot yet use different beams. In contrast, with time-domain beamforming all the users and signals in a time slot use the same beam. Hybrid beamforming allows different users in the same time slot to use different beams (the frequency-domain part) at the same time as all the users using a shared time-domain beam. An example is the case where the time-domain beam provides directivity in the elevation plane (so all users use the same elevation beam) while the frequency-domain beams provide directivity in the azimuth plane (so different users may use different azimuth beams). The following beamforming methods are supported: a) Predefined-beam beamforming: In this case, an index called “beamId” indicates thespecific beam pre-defined in the O-RU to use. The beamId can indicate a frequency- domain beam or a time-domain beam or a combination of both (“hybrid" beam) and the O-DU needs to know it to ensure the beamId is properly applied e.g. the O-DU cannot apply different time-domain beams to the different PRBs in the same OFDM symbol. The method the O-RU uses to generate the beam is otherwise not relevant, it could use the application of gain and phase controls on separate antenna elements, or use multiple shaped-energy antennas, or any other technology. The O-RU should convey to the O-DU via the M-Plane on startup beam characteristics but the O-DU may remain ignorant regarding how the beam is actually created by the O-RU. If the multiple beamId tables feature is configured via the M-Plane as specified in clause 15.4.6 of the M-Plane specification, then the beamId value (and the associated pre-defined beam) is specific to the beamId table configured (via M-Plane parameter configured-tx-beamId-table-index) for the array carrier associated with the eAxC receiving the beamId value. Otherwise, the association of the beamId value and the pre-defined beam is global per O-RU (see also clause 7.5.3.9). b) Weight-based dynamic beamforming (based on real-time-updated weights): Here the O-DU is meant to generate weights that create the beam, so the O-DU needs to know the specific antenna characteristics of the O-RU including how many antenna elements are present in the vertical and horizontal directions and the antenna element spacing, among other properties. The weight vector associated with each beam has a beamId value and the interpretation of this beamId value is addressed in clause 12.4.3. If the multiple beamId tables feature is configured via the M-Plane as specified in clause 15.4.6 of the M-Plane specification, then the beamId value (and the associated weigh vector) is specific to the beamId table configured (via M-Plane parameter configured-tx-beamId- table-index) for the array carrier associated with the eAxC receiving the beamId value.Otherwise, the association of the beamId value and the weigh vector is global per O-RU (see also clause 7.5.3.9).c) Attribute-based dynamic beamforming (based on real-time-updated beam attributes):Like predefined-beam beamforming, attribute-based beamforming allows the O-DU to tell the O-RU to use a specific beamId but in this case that beamId is associated with certain beam attributes as described in clause 7.7.2. How the O-RU achieves the implementation of the beams is not specified, however the O-DU needs to know whether the beam identified by the beamId is generated as a frequency-domain beam or a time- domain beam to ensure the beamId is properly applied e.g. the O-DU cannot apply different time-domain beams to the different PRBs in the same OFDM symbol. When the attribute-based beamforming method is used for at least one layer (or spatial stream), then O-DU shall use same beamforming method for all layers (or spatial streams) of the specific time-frequency resource element(s). If the multiple beamId tables feature is configured via the M-Plane as specified in clause 15.4.6 of the M-Plane specification, then the beamId value (and the associated set of attributes) is specific to the beamId table configured (via M-Plane parameter configured-tx-beamId-table-index) to be used for the array carrier associated with the eAxC receiving the beamId value. Otherwise, the association of the beamId value and the set of attributes is global per O-RU (see also clause 7.5.3.9).d) Channel-information-based beamforming: In this case the O-DU provides channelinformation per UE periodically (generally less often than every slot) and then on a slot- by-slot basis the O-DU provides scheduling information which the O-RU uses along with the channel information to calculate the proper beamforming weights for the specific slot with its co-scheduled UEs. Here there is no beamId value associated with the beamforming, instead the ueId is associated with each data section. Therefore, this clause regarding beamId usage is not relevant for this beamforming method. When the channel- information-based beamforming method is used for at least one layer (or spatial stream), then O-DU shall use same beamforming method for all layers (or spatial streams) of the specific time-frequency resource element(s). The multiple beamId tables feature is not applicable for channel-information-based beamforming.e) DMRS-based beamforming: In this case the O-DU provides a description of the DMRSconfiguration for PUSCH, and the O-RU uses that description to perform channel estimation and compute beamforming weights with or without an equalization function from the DMRS data and applies the weights to the PUSCH data and optionally DMRS data. Because there is no use of beamId in this method, therefore, this clause regarding beamId usage is not relevant for this beamforming method. See clause 12.6 for a full description of DMRS-BF.f) Codebook-based dynamic beamforming: In this case the O-DU provides information tothe O-RU describing the codebook, including e.g. rank indication and precoding matrix indication, and the O-RU uses the information to internally compute DL beamforming weights per subband and layer. The codebook information is associated to ueId on the fronthaul interface and does not use any beamId for precoding. However, beamId is used for mapping precoded data from CSI-RS ports (logical array) to tx-array elements, allowing support for beamformed CSI-RS12.4.2 Predefined-beam beamforming (PDBF) 12.4.3 Weight-based dynamic beamforming (WDBF) 12.4.4 Attribute-based dynamic beamforming (ABBF) 12.4.5 Channel-information-based beamforming (CIBF) 12.4.6 DMRS based beamforming (DMRS-BF) 12.4.7 Codebook-based dynamic beamforming (CDBF) In Codebook-based dynamic beamforming (CDBF), the O-DU sends codebook information that can represent different precoding from user layers to CSI-RS ports for different subbands and layers. The precoding codebook information is connected to ueId in Section Type 5 and does not require beamId. Instead, beamId is used for mapping / beamforming from CSI-RS ports (precoder output) to tx-array elements. This mapping can be done using beamId in different ways depending on SE ZZ parameter p2aMappingType. More information is found in clause 12.7.4. 12.7 Codebook-based dynamic beamforming (CDBF) 12.7.1 Overview 3GPP defines DL codebooks to use with UE reporting of Rank Indication (RI) and Precoding Matrix Indication (PMI). For most of these codebooks, the CSI-RS antenna ports (often denoted CSI-RS ports) form a dual-polarized logical antenna array with dimensions 2×N1×N2, see 3GPP TS 38.214, clause 5.2.2.2. The codebook precoding may be different for different subbands. Codebook-based dynamic beamforming (CDBF) is a beamforming method for downlink in Category B O-RUs with a dual-polarized tx-array, where conceptually a first precoding step using a codebook expands from number of layers to number of CSI-RS ports, and a second step maps from CSI-RS ports to antenna (tx-array elements) using beamId(s). CDBF reduces the amount of C-plane information compared with WDBF since the O-DU does not need to convey beamIds and beamforming weights per subband and layer. A CDBF codebook and its mapping to a tx-array is described by Section Extension ZZ sent with ST 5 (and optionally also SE 10) in every slot where CDBF is desired (no codebook persistence). Without CDBF, the O-DU could send CSI-RS using one set of beamIds (using e.g. PDBF or WDBF), and then use WDBF and define new beamIds referring to a combination of the codebook and the array mapping weights (matrix multiplication of the port-to-antenna weight matrix and the precoding weight matrix). Such combination of codebook and mapping would be needed for each subband. The CDBF method is valuable for codebook-based beamforming, especially in Massive MIMOconfigurations with many antennas and layers. Codebooks are in general defined for a user group (see clause 3.1 for a definition), e.g.3GPP Type I codebooks, which are intended for SU-MIMO. High-level operation of CDBF is as follows: 1) An O-RU supporting CDBF shall declare one or more tx-arrays including bothpolarizations. 2) The O-RU shall declare support for delay profiles associated with specific BF methodsincluding CDBF. 3) The O-RU shall declare support for CDBF-specific capabilities including ueId format aswell as codebook types with restrictions. The O-RU shall also declare supported spatial configurations per tx-array. 4) For each slot where CDBF is used, the O-DU shall issue C-Plane messages using ST 5describing the scheduling decisions for each user group, shall use SE ZZ to convey CDBF information, and may use SE 10 (e.g. if there is more than one UE layer in the user group) but an O-RU supporting CDBF shall support receiving one SE ZZ per UE layer. 5) For each slot where CDBF is used, the O-RU shall:a. Determine beamforming weights per UE layer and subband, based on precoderand port-to-antenna mapping description sent by the O-DU. b. Apply the determined beamforming weights to each UE layer’s U-Plane IQ-data(e.g. PDSCH). 12.7.2 CDBF capability declaration and configuration via M-Plane An O-RU supporting CDBF shall support Section Type 5 and it shall also support M-Plane feature POINT-A-OFFSET-TO-ABSOLUTE-FREQUENCY-CENTER. Further, an O-RU that supports both CDBF and modulation compression shall support Section Extension 23 (both PRB MASK mode and PRB BLOCK mode) to avoid repeating codebook information when different mcScaleOffset values are used in a slot. An O-RU supporting CDBF shall declare the following: 1) Support for CDBF on O-RU level2) Support for Section Extension ZZ (and other capabilities) per endpoint-type.3) Supported maximum number of bits to represent UE layer, ueid-max-layer-bits (limitsthe max rank that can be supported) and maximum number of codebook types used, codebook-types-max-num-used (at least 1), maximum number of spatial configurations used, cdbf-spatial-configs-max-used (at least 1), and maximum number of PRB blocks in p2aMapping, max-prb-blks-per-sec-ext-ZZ (at least 1). 4) Support, per endpoint supporting CDBF, of one or more "beamforming delay profiles",with each beamforming delay profile containing a single delay profile which is associated with one or more beamforming methods including CDBF, as well as possibly other beamforming methods that work with the delay profile. 5) Supported CDBF codebook types per endpoint-type supporting CDBF: list codebook-types-supported with following parameters and where there can be multiple entries forsame codebook-type if other fields are different. This means that the codebook-type cannot be used as a unique index into the list. -codebook-type: selected value from enumeration of codebook types (theenumeration can be extended with additional types, e.g., variants of Type II codebooks, or codebooks for other radio access technologies): oNR-TYPE-1-SINGLE-PANEL-CBMODE-1 = 1 / / NR Type I single-panel,codebookMode = 1 oNR-TYPE-1-SINGLE-PANEL-CBMODE-2 = 2 / / NR Type I single-panel,codebookMode = 2 -max-rank: max supported rank for this codebook type.- max-num-csi-rs-ports: maximum number of CSI-RS ports supported for thiscodebook type. -max-num-subbands: maximum number of subbands that can be used for eachcodebook type. This can affect the minimum subband size used by the O-DU in SE ZZ codebook description.6) Supported spatial configurations per tx-array in list cdbf-spatial-configs-supported.Entries shall be listed in ascending order of number of CSI-RS ports (2×N1×N2), i.e., lowest number of CSI-RS ports first. -N1: Number of elements of the logical array of CSI-RS ports along N1dimension -N2: Number of elements of the logical array of CSI-RS ports along N2dimension -O1: DFT oversampling along N1 dimension- O2: DFT oversampling along N2 dimension- n2-is-cols: Flag indicating if logical array dimension N2 represents rows (FALSE) orcolumns (TRUE). An O-DU intending to use CDBF shall configure the following:1) To use a specific beamforming delay profile, one of the declared supported beamformingdelay profiles (see clause 12.7.2.1 item 4) for that endpoint.2) To use a specific list of beamforming methods, which shall be a subset of the full list ofbeamforming methods associated with the configured beamforming delay profile.3) The parameter ueid-layer-bits-configured, which shall be less than or equal to ueid-max-layer-bits.4) The codebook types it indends to use, in list codebook-types-used. The O-DU shall notconfigure (enable) more than O-RU declared limit codebook-types-max-num-used codebook types.5) The spatial configurations it intends to use, in list cdbf-spatial-configs-used, whichcontains indices to O-RU declared read-only list cdbf-spatial-configs-supported. The O-DU shall not configure more than O-RU declared limit cdbf-spatial-configs-max-used number of spatial configurations. 6) The offset to Point A in per-carrier parameter point-a-offset-to-absolute-frequency-centerunless Point A coincides with RE #0 of PRB #0. 12.7.3 Codebook aspects 3GPP codebooks based on reporting of Precoding Matrix Indication (PMI) and Rank Indication (RI) for a given spatial configuration typically consists of a wideband codebook part and one or more subband codebook parts, see 3GPP TS 38.214 clause 5.2.2.1. The wideband part contains a number of codebook indices (e.g. i1,1, i1,2, and i1,3for type I single-panel) that are conveyed in SE ZZ parameter codebookIndex1. The subband parts (e.g. i2 for type I single-panel) are conveyed in SE ZZ parameter codebookIndex2. The spatial configurations supported by the O-RU are declared in M-Plane list cdbf-spatial-configs-supported. The O-DU selects the spatial configurations it wants to use by M-Plane configuration in list cdbf-spatial-config-used and the configuration to use for a particular transmission is conveyed by indexing into this list using SE ZZ parameter spatialConfigIndex. The subbands in PMI reporting are defined on the 3GPP-defined CRB grid, which is not always aligned with the PRB grid on which a UE is scheduled. If the gNB wants to follow the PMI as reported, the O-RU needs to know the offset between CRB and PRB grid, which can be determined from M-plane parameter point-a-offset-to-absolute-frequency-center. Using this information together with SE ZZ parameter subbandSize and the number of PRBs described by the section description, the O-RU can determine number of subbands, and also which PRBs belong to each subband. Subbands at the edges of the range covered by the section description can contain fewer PRBs than subbands in the interior of the range if the CRB and PRB grids are not aligned for a given subband size. When a particular codebook uses fewer bits for an index than the corresponding fieldsize in SE ZZ, the indices shall be placed in the LSBs of the corresponding SE ZZ field while the unused MSBs shall be set to zero by the O-DU. The 5G NR Type I single-panel codebook variants are described in 3GPP TS 38.214, clause 5.2.2.2.1. one type for codebookMode = 1 and another type for codebookMode = 2. With the exception of 1-layer and 2-layer Channel State Information (CSI) reporting for two antenna ports (two CSI-RS ports), all Type I single-panel codebooks are based on oversampled DFT beams and a logical array of (N1, N2) CSI-RS ports with two polarizations, i.e., PCSI-RS = 2×N1×N2 CSI- RS ports. Codebook indices are used to select e.g., beams and phase relation between polarizations, including a wideband part and a per-subband part. Different enumeration values ofparameter codebook-type in M-Plane declared list codebook-types-supported are assigned to Type I single-panel codebook depending on 3GPP parameter codebookMode. 3GPP TS 38.214, Table 5.2.2.2.1-1 describes an exception from oversampled DFT codebooks. In CDBF it shall be supported for Type I single-panel codebook with codebookMode = 1 and mapped to the two-port spatial configuration (N1, N2) = (1, 1), with (O1, O2) = (1, 1). The codebook index specified by 3GPP in that table shall be conveyed in index i2 in SE ZZ: the two least significant bits are used for single-layer codebook index, while the least significant bit is used for two-layer codebook index. The different parts of the composite i1 index in codebookIndex1 shall all be set to 0. For the remaining Type I single-panel codebooks, indices within SE ZZ codebookIndex1 (containing the wideband i1indices) and codebookIndex2 (containing the subband i2 indices) are used according to the definitions in 3GPP TS 38.214, clause 5.2.2.2.1. The codebook can be determined based on rank, spatial configuration, and number of CSI-RS ports. 12.7.4 Port-to-antenna mapping aspects Transmission of CSI-RS is not affected by CDBF and can be done without beamforming, or with beamforming (e.g. PDBF or WDBF). However, it is typically desired to use same beamforming (if any) on the output of the codebook precoder as was used on the CSI-RS transmissions. For most 3GPP codebooks, the CSI-RS ports represent a logical dual-polarized rectangular antenna array with dimensions N1 and N2 but 3GPP does not define which of these dimensions is horizontal and which is vertical. Since it is important that the O-DU and O-RU agree on the orientation, a flag is included in the O-RU’s list of supported spatial configurations. Polarization mapping is the same between 3GPP and the current specification, i.e., first half of ports of array elements represent first polarization while second half of array elements represent second polarization. When multiple beamIds are involved, the order of beamIds (which beamId belongs to which CSI-RS port) should take into account the fact that element numbering can differ between the 3GPP (N1, N2) logical array and the physical tx-array antenna model in clause 12.5.4 of the present document.3GPP does not specify which dimension is vertical and which is horizontal since the UE does not need to know this. However, for CDBF the O-DU and O-RU needs to agree on which dimension is vertical (representing rows) and which is horizontal (representing columns). For each supported spatial configuration tuple in the M-plane defined list cdbf-spatial- configs-supported, the O-RU shall set the flag ‘n2-is-cols’ to TRUE if N2 represents columns, and FALSE if N2 represents rows. Since N1 ≥ N2 for all supported combinations in 3GPP TS 38.214 Table 5.2.2.2.1-2, it is necessary to set the logical array orientation depending on if more rows or more columns are desired in the logical array.CSI-RS ports are enumerated first over the N2 dimension and then over the N1 dimension (starting in bottom left of the logical array), while the antenna model in clause 12.5.4 of the current specification enumerates array elements in column-major order (also starting in bottom left). Different types of mapping are possible, including flexible variants with one beamId per CSI-RS port and more resource-efficient variants with a single beamId for all CSI-RS ports. Different mapping for different PRB ranges is also possible. An example of disjoint uniform mapping from port to antenna where N2represents rows of the logical array is shown in Figure 12.7.4.1-1 while an example where N2 represents columns is shown in Figure 12.7.4.1-2. The type of polarization (e.g. V / H or cross-polarized) does not impact CDBF operation but the first half of the CSI-RS ports shall map to the first polarization of the array. Figure 12.7.4.1-1: Example of disjoint uniform mapping from 16 CSI-RS ports to a 64-element tx-array when N2represents rows (n2-is-cols = FALSE) in the logical array of CSI-RS ports, reproduced herein as Figure 5. NOTE: Actual polarizations can differ from those in the figure but the first half of CSI-RS ports map to the first polarization in the tx-array while the second half of CSI-RS ports map to the second polarization. Figure 12.7.4.1-2: Example of disjoint uniform mapping from 16 CSI-RS ports to a 64-element 64 Tx-array when N2 represents columns (n2-is-cols = TRUE) in the logical array of CSI-RS ports, reproduced as Figure 6. NOTE: Actual polarizations can differ from those in the figure but the first half of CSI-RS ports map to the first polarization in the tx-array while the second half of CSI-RS ports map to the second polarization. The number of CSI-RS ports, PCSI-RS, can be determined from the O-DU configured M-plane list cdbf-spatial-configs-used referred to by parameter spatialConfigIndex in Section Extension ZZ. Each entry in the list contains an index into an O-RU supported spatial configuration declared in list cdbf-spatial-configs-supported. SE ZZ supports different mapping types: ^p2aMappingType 0000b: Explicit mapping where a list of PCSI-RS beamIds (one per CSI-RS port) are included in SE ZZ. This is the most flexible option and it can handle any linear mapping. The list of beamIds are used for all PRBs. ^p2aMappingType 0001b: Explicit mapping where SE ZZ includes the first beamId in arange of PCSI-RS consecutive beamIds (one per CSI-RS port). This option can handle same mappings as type 0001b but restricts the beamIds to be consecutive, thus allowing reduction of the amount of information in the C-Plane message. By using non-zero value of parameter prbBlkSize and specifying one “first beamId” per PRB block, differentmapping for different PRB ranges is possible. The maximum number of PRB blocks is limited by the O-RU declared parameter max-prb-blks-per-sec-ext-ZZ. ^p2aMappingType 0010b: Implicit mapping where SE ZZ includes a single beamId andwhere disjoint parts of the beamId weight vector are applied for each CSI-RS port. CSI- RS ports are mapped to disjoint uniform rectangles of tx-array elements using implicit antenna masks determined by the O-RU. Beamforming weights for the mapping are taken from respective parts of the weight vector pointed to by beamId. If parameter beamId is set to 0x0000 (no BF), unity weights shall be applied by the O-RU, which means that the mapping just involves copying precoder output to the tx-array elements indicated by the implicit antenna mask. By using non-zero value of parameter prbBlkSize and specifying one beamId per PRB block, different mapping for different PRB ranges is possible. The maximum number of PRB blocks is limited by the O-RU declared parameter max-prb-blks-per-sec-ext-ZZ. For p2aMappingType 0000b and 0001b, each CSI-RS port can be mapped to the full array with individual beamforming weights (BFW) for each tx-array element. However, in many common cases, e.g. rectangular uniformly-spaced arrays where the number of elements per dimension is an integer multiple of the CSI-RS port configuration, a large number of beamforming weights will be zero if each CSI-RS port maps to a disjoint set of tx-array elements. For the example in Figure 12.7.4.1-1, the BFW vector for CSI-RS port 0 has non-zero weights only for tx-array elements {0, 1, 8, 9} while the BFW vectors for all other CSI-RS ports have zero-valued weights for these tx-array elements. This means that the total number of non-zero weights summed over all CSI-RS ports is equal to the number of tx-array elements and can thus be stored with a single beamId. This is utilized in p2aMappingType 0010b, where a single beamId and corresponding beamforming weight vector is shared by all CSI-RS ports. For p2aMappingType 0010b, implicit antenna masks per CSI-RS port are used to determine which subset of beamforming weights to apply for each CSI-RS port. These antenna masks canbe determined based on spatialConfigIndex. For the logical array of CSI-RS ports, numbered ^^ =0,1, … ,^^^^^^^^−^^^^ − 1, the position along the N1 axis is ^^1 = (⌊^^ / ^^2⌋ ^^^^^^ ^^1), the position alongthe N axis as ^^ = (^^ ^^^^^ 22 ^^^ ^^2), and the polarization index is ^^ = ⌊^^1^^2⌋. N1and N2are defined according to 3GPP TS 38.214 clause 5.2.2.2. Further, m, n, M, P are as described foridentification and ordering of array elements in clause 12.5.4 of the present document.When n2-is-cols = FALSE, N2 represents row dimension. CSI-RS port ^^ = 0,1, … ,^^^^^^^^−^^^^ − 1maps to column n, row m, and polarization p in the tx-array as follows, where the implicit antenna mask of port j is set to true for those array elements where the expressions are valid: ^^(^^ + 1)^^ì1^^ ≤^^ < 1ï ^^1^^1^^When n2-is-cols = TRUE, N2 represents column dimension. CSI-RS port ^^ = 0,1, … ,^^^^^^^^−^^^^ − 1maps to tx-array column n, row m, and polarization p as follows, where the implicit antenna mask of port j is set to true for those array elements where the expressions are valid: ^^(^^ + 1)^^ì2^^ ≤^^ < 2ï ^^2^^2^^*****************************************************************************

[0136] Figure 7 illustrates an example of a communication system 100 in accordance withsome embodiments. In the example, the communication system 100 includes a telecommunication network 102 that includes an access network 104, such as a radio access network (RAN), and a core network 106, which includes one or more core network nodes 108. The access network 104 includes one or more access network nodes, such as network nodes 110a and 110b (one or more of which may be generally referred to as network nodes 110), or any other similar 3rd Generation Partnership Project (3GPP) access node or non-3GPP access point. The network nodes 110 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 112a, 112b, 112c, and 112d (one or more of which may be generally referred to as UEs 112) to the core network 106 over one or more wireless connections.

[0137] Example wireless communications over a wireless connection include transmittingand / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 100 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 100 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0138] The UEs 112 may be any of a wide variety of communication devices, includingwireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 110 and other communication devices. Similarly, the network nodes 110 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 112 and / or with other network nodes or equipment in the telecommunication network 102 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 102.

[0139] In the depicted example, the core network 106 connects the network nodes 110 to oneor more hosts, such as host 116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 106 includes one more core network nodes (e.g., core network node 108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0140] The host 116 may be under the ownership or control of a service provider other thanan operator or provider of the access network 104 and / or the telecommunication network 102, and may be operated by the service provider or on behalf of the service provider. The host 116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0141] As a whole, the communication system 100 of Figure 7 enables connectivity betweenthe UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0142] In some examples, the telecommunication network 102 is a cellular network thatimplements 3GPP standardized features. Accordingly, the telecommunications network 102 may support network slicing to provide different logical networks to different devices that areconnected to the telecommunication network 102. For example, the telecommunications network 102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive IoT services to yet further UEs.

[0143] In some examples, the UEs 112 are configured to transmit and / or receive informationwithout direct human interaction. For instance, a UE may be designed to transmit information to the access network 104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 104. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio – Dual Connectivity (EN-DC).

[0144] In the example, the hub 114 communicates with the access network 104 to facilitateindirect communication between one or more UEs (e.g., UE 112c and / or 112d) and network nodes (e.g., network node 110b). In some examples, the hub 114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 114 may be a broadband router enabling access to the core network 106 for the UEs. As another example, the hub 114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 110, or by executable code, script, process, or other instructions in the hub 114. As another example, the hub 114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 114 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 114 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 114 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy IoT devices.

[0145] The hub 114 may have a constant / persistent or intermittent connection to the networknode 110b. The hub 114 may also allow for a different communication scheme and / or schedule between the hub 114 and UEs (e.g., UE 112c and / or 112d), and between the hub 114 and the core network 106. In other examples, the hub 114 is connected to the core network 106 and / or one or more UEs via a wired connection. Moreover, the hub 114 may be configured to connect to an M2M service provider over the access network 104 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 110 while stillconnected via the hub 114 via a wired or wireless connection. In some embodiments, the hub 114 may be a dedicated hub – that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 110b. In other embodiments, the hub 114 may be a non- dedicated hub – that is, a device which is capable of operating to route communications between the UEs and network node 110b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0146] Figure 8 shows a UE 200 in accordance with some embodiments. As used herein, aUE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0147] A UE may support device-to-device (D2D) communication, for example byimplementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to- everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0148] The UE 200 includes processing circuitry 202 that is operatively coupled via a bus 204to an input / output interface 206, a power source 208, a memory 210, a communication interface 212, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 8. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0149] The processing circuitry 202 is configured to process instructions and data and may beconfigured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 210. The processing circuitry 202 may beimplemented as one or more hardware-implemented state machines (e.g., in discrete logic, field- programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 202 may include multiple central processing units (CPUs).

[0150] In the example, the input / output interface 206 may be configured to provide aninterface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0151] In some embodiments, the power source 208 is structured as a battery or battery pack.Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 208 may further include power circuitry for delivering power from the power source 208 itself, and / or an external power source, to the various parts of the UE 200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 208 to make the power suitable for the respective components of the UE 200 to which power is supplied.

[0152] The memory 210 may be or be configured to include memory such as random accessmemory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 210 includes one or more application programs 214, such as an operating system, web browser application, a widget, gadget engine, or otherapplication, and corresponding data 216. The memory 210 may store, for use by the UE 200, any of a variety of various operating systems or combinations of operating systems.

[0153] The memory 210 may be configured to include a number of physical drive units, suchas redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 210 may allow the UE 200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 210, which may be or comprise a device-readable storage medium.

[0154] The processing circuitry 202 may be configured to communicate with an accessnetwork or other network using the communication interface 212. The communication interface 212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 222. The communication interface 212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 218 and / or a receiver 220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 218 and receiver 220 may be coupled to one or more antennas (e.g., antenna 222) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0155] In the illustrated embodiment, communication functions of the communicationinterface 212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short- range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access(WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0156] Regardless of the type of sensor, a UE may provide an output of data captured by itssensors, through its communication interface 212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0157] As another example, a UE comprises an actuator, a motor, or a switch, related to acommunication 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.

[0158] A UE, when in the form of an Internet of Things (IoT) device, may be a device for usein 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 IoT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item- tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an IoT device comprises circuitry and / or software in dependence of the intended application of the IoT device in addition to other components as described in relation to the UE 200 shown in Figure 8.

[0159] As yet another specific example, in an IoT scenario, a UE may represent a machine orother 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 casebe 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 and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0160] In practice, any number of UEs may be used together with respect to a single use case.For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0161] Figure 9 shows a network node 300 in accordance with some embodiments. As usedherein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)).

[0162] Base stations may be categorized based on the amount of coverage they provide (or,stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0163] Other examples of network nodes include multiple transmission point (multi-TRP) 5Gaccess nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0164] The network node 300 includes a processing circuitry 302, a memory 304, acommunication interface 306, and a power source 308. The network node 300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 304 for different RATs) and some components may be reused (e.g., a same antenna 310 may be shared by different RATs). The network node 300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 300.

[0165] The processing circuitry 302 may comprise a combination of one or more of amicroprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 300 components, such as the memory 304, to provide network node 300 functionality.

[0166] In some embodiments, the processing circuitry 302 includes a system on a chip (SOC).In some embodiments, the processing circuitry 302 includes one or more of radio frequency (RF) transceiver circuitry 312 and baseband processing circuitry 314. In some embodiments, the radio frequency (RF) transceiver circuitry 312 and the baseband processing circuitry 314 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 312 and baseband processing circuitry 314 may be on the same chip or set of chips, boards, or units.

[0167] The memory 304 may comprise any form of volatile or non-volatile computer-readablememory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile ornon-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 302. The memory 304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 302 and utilized by the network node 300. The memory 304 may be used to store any calculations made by the processing circuitry 302 and / or any data received via the communication interface 306. In some embodiments, the processing circuitry 302 and memory 304 is integrated.

[0168] The communication interface 306 is used in wired or wireless communication ofsignaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 306 comprises port(s) / terminal(s) 316 to send and receive data, for example to and from a network over a wired connection. The communication interface 306 also includes radio front-end circuitry 318 that may be coupled to, or in certain embodiments a part of, the antenna 310. Radio front-end circuitry 318 comprises filters 320 and amplifiers 322. The radio front-end circuitry 318 may be connected to an antenna 310 and processing circuitry 302. The radio front-end circuitry may be configured to condition signals communicated between antenna 310 and processing circuitry 302. The radio front-end circuitry 318 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 320 and / or amplifiers 322. The radio signal may then be transmitted via the antenna 310. Similarly, when receiving data, the antenna 310 may collect radio signals which are then converted into digital data by the radio front-end circuitry 318. The digital data may be passed to the processing circuitry 302. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0169] In certain alternative embodiments, the network node 300 does not include separateradio front-end circuitry 318, instead, the processing circuitry 302 includes radio front-end circuitry and is connected to the antenna 310. Similarly, in some embodiments, all or some of the RF transceiver circuitry 312 is part of the communication interface 306. In still other embodiments, the communication interface 306 includes one or more ports or terminals 316, the radio front-end circuitry 318, and the RF transceiver circuitry 312, as part of a radio unit (not shown), and the communication interface 306 communicates with the baseband processing circuitry 314, which is part of a digital unit (not shown).

[0170] The antenna 310 may include one or more antennas, or antenna arrays, configured tosend and / or receive wireless signals. The antenna 310 may be coupled to the radio front-endcircuitry 318 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 310 is separate from the network node 300 and connectable to the network node 300 through an interface or port.

[0171] The antenna 310, communication interface 306, and / or the processing circuitry 302may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 310, the communication interface 306, and / or the processing circuitry 302 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0172] The power source 308 provides power to the various components of network node 300in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 308 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 300 with power for performing the functionality described herein. For example, the network node 300 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 308. As a further example, the power source 308 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0173] Embodiments of the network node 300 may include additional components beyondthose shown in Figure 9 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 300 may include user interface equipment to allow input of information into the network node 300 and to allow output of information from the network node 300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 300.

[0174] Figure 10 is a block diagram of a host 400, which may be an embodiment of the host116 of Figure 7, in accordance with various aspects described herein. As used herein, the host 400 may be or comprise various combinations hardware and / or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host 400 may provide one or more services to one or more UEs.

[0175] The host 400 includes processing circuitry 402 that is operatively coupled via a bus404 to an input / output interface 406, a network interface 408, a power source 410, and a memory 412. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 3 and 4, such that the descriptions thereof are generally applicable to the corresponding components of host 400.

[0176] The memory 412 may include one or more computer programs including one or morehost application programs 414 and data 416, which may include user data, e.g., data generated by a UE for the host 400 or data generated by the host 400 for a UE. Embodiments of the host 400 may utilize only a subset or all of the components shown. The host application programs 414 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application programs 414 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host 400 may select and / or indicate a different host for over-the-top services for a UE. The host application programs 414 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), etc.

[0177] Figure 11 is a block diagram illustrating a virtualization environment 500 in whichfunctions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 500 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized.

[0178] Applications 502 (which may alternatively be called software instances, virtualappliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0179] Hardware 504 includes processing circuitry, memory that stores software and / orinstructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 508a and 508b (one or more of which may be generally referred to as VMs 508), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 506 may present a virtual operating platform that appears like networking hardware to the VMs 508.

[0180] The VMs 508 comprise virtual processing, virtual memory, virtual networking orinterface and virtual storage, and may be run by a corresponding virtualization layer 506. Different embodiments of the instance of a virtual appliance 502 may be implemented on one or more of VMs 508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0181] In the context of NFV, a VM 508 may be a software implementation of a physicalmachine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 508, and that part of hardware 504 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 508 on top of the hardware 504 and corresponds to the application 502.

[0182] Hardware 504 may be implemented in a standalone network node with generic orspecific components. Hardware 504 may implement some functions via virtualization. Alternatively, hardware 504 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 510, which, among others, oversees lifecycle management of applications 502. In some embodiments, hardware 504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radiounits may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 512 which may alternatively be used for communication between hardware nodes and radio units.

[0183] Figure 12 shows a communication diagram of a host 602 communicating via a networknode 604 with a UE 606 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as a UE 112a of Figure 7 and / or UE 200 of Figure 8), network node (such as network node 110a of Figure 7 and / or network node 300 of Figure 9), and host (such as host 116 of Figure 7 and / or host 400 of Figure 10) discussed in the preceding paragraphs will now be described with reference to Figure 12.

[0184] Like host 400, embodiments of host 602 include hardware, such as a communicationinterface, processing circuitry, and memory. The host 602 also includes software, which is stored in or accessible by the host 602 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE 606 connecting via an over-the-top (OTT) connection 650 extending between the UE 606 and host 602. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 650.

[0185] The network node 604 includes hardware enabling it to communicate with the host602 and UE 606. The connection 660 may be direct or pass through a core network (like core network 106 of Figure 7) and / or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

[0186] The UE 606 includes hardware and software, which is stored in or accessible by UE606 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE 606 with the support of the host 602. In the host 602, an executing host application may communicate with the executing client application via the OTT connection 650 terminating at the UE 606 and host 602. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection 650 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection 650.

[0187] The OTT connection 650 may extend via a connection 660 between the host 602 andthe network node 604 and via a wireless connection 670 between the network node 604 and the UE 606 to provide the connection between the host 602 and the UE 606. The connection 660 and wireless connection 670, over which the OTT connection 650 may be provided, have been drawn abstractly to illustrate the communication between the host 602 and the UE 606 via the network node 604, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

[0188] As an example of transmitting data via the OTT connection 650, in step 608, the host602 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE 606. In other embodiments, the user data is associated with a UE 606 that shares data with the host 602 without explicit human interaction. In step 610, the host 602 initiates a transmission carrying the user data towards the UE 606. The host 602 may initiate the transmission responsive to a request transmitted by the UE 606. The request may be caused by human interaction with the UE 606 or by operation of the client application executing on the UE 606. The transmission may pass via the network node 604, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 612, the network node 604 transmits to the UE 606 the user data that was carried in the transmission that the host 602 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 614, the UE 606 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 606 associated with the host application executed by the host 602.

[0189] In some examples, the UE 606 executes a client application which provides user datato the host 602. The user data may be provided in reaction or response to the data received from the host 602. Accordingly, in step 616, the UE 606 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input / output interface of the UE 606. Regardless of the specific manner in which the user data was provided, the UE 606 initiates, in step 618, transmission of the user data towards the host 602 via the network node 604. In step 620, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 604 receives user data from the UE 606 and initiates transmission of the received user data towards the host 602. In step 622, the host 602 receives the user data carried in the transmission initiated by the UE 606.

[0190] One or more of the various embodiments improve the performance of OTT servicesprovided to the UE 606 using the OTT connection 650, in which the wireless connection 670 forms the last segment. More precisely, the teachings of these embodiments may improve the delay todirectly activate an SCell by RRC and power consumption of user equipment and thereby provide benefits such as reduced user waiting time and extended battery lifetime.

[0191] In an example scenario, factory status information may be collected and analyzed bythe host 602. As another example, the host 602 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 602 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 602 may store surveillance video uploaded by a UE. As another example, the host 602 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host 602 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and / or transmitting data.

[0192] In some examples, a measurement procedure may be provided for the purpose ofmonitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 650 between the host 602 and UE 606, in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host 602 and / or UE 606. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 650 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 650 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node 604. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host 602. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 650 while monitoring propagation times, errors, etc.

[0193] Figure 13 is a flowchart illustrating an example method performed by an O-DUnetwork node. In particular embodiments, one or more steps of Figure 13 may be performed by network node 300 described with respect to Figure 9. The network node is capable of codebook- based dynamic beamforming.

[0194] The method may begin at step 1302, where the network node (e.g., network node 300of Figure 9) receives from the O-RU an indication of spatial configurations supported by the O- RU, and at step 1304, the network node may transmit to the O-RU an indication of one or more spatial configurations that the O-DU intends to use. Steps 1302 and 1304 may be performed via the management plane and are described in more detail above.

[0195] The spatial configuration may comprise an indication of a number of rows andcolumns in the logical array of logical ports (e.g., N1, N2). The spatial configuration may further comprise an indication of discrete Fourier transform beam oversampling in each of vertical and horizontal directions for the logical array of logical ports (e.g., O1, O2). In particular embodiments, the spatial configuration may comprise any of the spatial configuration described with respect to the embodiments and examples disclosed herein.

[0196] At step 1306, the network node may receive from the O-RU an indication of codebooktypes supported by the O-RU, and at step 1308, the network node may transmit to the O-RU an indication of one or more codebook types that the O-DU intends to use. Steps 1306 and 1308 may be performed via the management plane and are described in more detail above.

[0197] In some embodiments, the codebook type may indicate one of Type I single / multipanel or Type II variants. In some embodiments, the codebook type may comprise an indication of one or more of a maximum supported rank, a maximum number of CSI-RS ports, and a maximum number of subbands for the type.

[0198] In particular embodiments, the codebook type may comprise any of the codebooktypes described with respect to the embodiments and examples disclosed herein.

[0199] At step 1310, the network node transmits, to an O-RU, control plane informationcomprising: a port-to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports.

[0200] In particular embodiments, the control plane information further comprises anindication of a codebook type.

[0201] In particular embodiments, the codebook description may further comprise a widebandpart and a subband part. For example, the codebook description may include a plurality of parameters (for beam selection, cophasing between polarizations, and optionally also beam combining weights) describing the wideband and per-subband parts of the codebook precoding.

[0202] In particular embodiments, each logical port of the array of logical ports is mapped toa disjoint rectangle of antennas in the physical transmit array and wherein the port-to-antenna mapping comprises a single beamforming weight vector and associated beam identifier mappingall logical ports to the physical transmit antenna array. For example, the mapping may comprise one beamId for multiple ports, together with implicit antenna masks that may be determined from the spatial configuration and the O-RU antenna configuration.

[0203] In particular embodiments, the port-to-antenna mapping comprises one beam formingweight tensor for a vertical direction of the physical antenna array and one beam forming weight tensor for a horizontal direction of the physical antenna array.

[0204] In particular embodiments, the port-to-antenna mapping comprises more than oneport-to-antenna mapping each associated with a different frequency range.

[0205] In particular embodiments, the control plane information further comprises any one ormore of: a power scaling parameter; a tapering parameter; signal quality information; and an indication of a pre-precoder.

[0206] In particular embodiments, the codebook description comprises any of the codebookdescriptions described with respect to the embodiments and examples disclosed herein.

[0207] In particular embodiments, the port-to-antenna mapping comprises any of the port-to-antenna mappings described with respect to the embodiments and examples disclosed herein.

[0208] At step 1312, the network node transmits user plane information to the O-RU. Theuser plane information is to be transmitted by the O-RU to a wireless device according to the port- to-antenna mapping, codebook description, and spatial configuration.

[0209] Modifications, additions, or omissions may be made to method 1300 of Figure 13.Additionally, one or more steps in the method of Figure 13 may be performed in parallel or in any suitable order.

[0210] Figure 14 is a flowchart illustrating an example method performed by an O-RUnetwork node, according to certain embodiments. In particular embodiments, one or more steps of Figure 14 may be performed by network node 300 described with respect to Figure 9. The network node is capable of codebook-based dynamic beamforming.

[0211] The method may begin at step 1402, where the network node (e.g., network node 300of Figure 9) transmits to the O-DU an indication of spatial configurations supported by the O-RU, and at step 1404, the network node receives from the O-DU an indication of one or more spatial configurations that the O-DU intends to use. The steps are described with respect to Figure 13 and in more detail with respect to the embodiments and examples disclosed herein.

[0212] At step 1406, the network node may transmit to the O-DU an indication of codebooktypes supported by the O-RU, and at step 1408, the network node may receive from the O-DU an indication of one or more codebook types that the O-DU intends to use. The steps are described with respect to Figure 13 and in more detail with respect to the embodiments and examples disclosed herein.

[0213] At step 1410, the network node may receive, from an O-DU, control plane informationcomprising: a port-to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports. This step is described with respect to Figure 13 and in more detail with respect to the embodiments and examples disclosed herein.

[0214] At step 1412, the network node receives user plane information from the O-DU fortransmission to a wireless device.

[0215] At step 1414, the network node generates a beamforming weight matrix for thewireless device based on the port-to-antenna mapping, codebook description, and spatial configuration. The network node generates the beamforming weight matrix according to any of the embodiments and examples disclosed herein.

[0216] At step 1416, the network node transmits the user plane information to the wirelessdevice according to the generated beamforming weight matrix. The network node transmits the user plane information according to any of the embodiments and examples disclosed herein.

[0217] Modifications, additions, or omissions may be made to method 1400 of Figure 14.Additionally, one or more steps in the method of Figure 14 may be performed in parallel or in any suitable order.

[0218] The foregoing description sets forth numerous specific details. It is understood,however, that embodiments may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.

[0219] References in the specification to “one embodiment,” “an embodiment,” “an exampleembodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0220] 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 softwareneeded 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.

[0221] In certain embodiments, some or all of the functionality described herein may beprovided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

Claims

CLAIMS 1. A method performed by an open radio access network, O-RAN, distributed unit, O- DU, network node for codebook-based dynamic beamforming, the method comprising: transmitting (1310), to an O-RAN radio unit, O-RU, control plane information comprising: a port-to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports; and transmitting (1312) user plane information to the O-RU, the user plane information to be transmitted by the O-RU to a wireless device according to the port-to-antenna mapping, codebook description, and spatial configuration.

2. The method of claim 1, further comprising receiving (1302) from the O-RU an indication of spatial configurations supported by the O-RU.

3. The method of any one of claims 1-2, further comprising transmitting (1304) to the O- RU an indication of one or more spatial configurations that the O-DU intends to use.

4. The method of any one of claims 1-3, wherein the spatial configuration comprises an indication of a number of rows and columns in the logical array of logical ports.

5. The method of claim 4, wherein the spatial configuration further comprises an indication of discrete Fourier transform beam oversampling in each of vertical and horizontal directions for the logical array of logical ports.

6. The method of any one of claims 1-5, wherein the control plane information further comprises an indication of a codebook type.

7. The method of any one of claims 1-6, further comprising receiving (1306) from the O- RU an indication of codebook types supported by the O-RU.

8. The method of any one of claims 1-7, further comprising transmitting (1308) to the O- RU an indication of one or more codebook types that the O-DU intends to use.

9. The method of any one of claims 6-8, wherein the codebook type comprises an indication of one or more of a maximum supported rank, a maximum number of channel state information reference signal, CSI-RS, ports, and a maximum number of subbands for the type.

10. The method of any one of claims 1-9, wherein the codebook description further comprises a wideband part and a subband part.

11. The method of any one of claims 1-10, wherein each logical port of the array of logical ports is mapped to a disjoint rectangle of antennas in the physical transmit array and wherein the port-to-antenna mapping comprises a single beamforming weight vector and associated beam identifier mapping all logical ports to the physical transmit antenna array.

12. The method of any one of claims 1-11, wherein the port-to-antenna mapping comprises one beam forming weight tensor for a vertical direction of the physical antenna array and one beam forming weight tensor for a horizontal direction of the physical antenna array.

13. The method of any one of claims 1-12, wherein the port-to-antenna mapping comprises more than one port-to-antenna mapping each associated with a different frequency range.

14. The method of any of one of claims 1-13, wherein the control plane information further comprises any one or more of: a power scaling parameter; a tapering parameter; signal quality information; and an indication of a pre-precoder.

15. An open radio access network, O-RAN, distributed unit, O-DU, network node (300) capable of codebook-based dynamic beamforming, the network node comprising processing circuitry (302) configured to: transmit, to an O-RAN radio unit, O-RU, control plane comprising: a port-to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; anda spatial configuration for a logical array of the logical ports; and transmit user plane information to the O-RU, the user plane information to be transmitted by the O-RU to a wireless device according to the port-to-antenna mapping, codebook description, and spatial configuration.

16. The network node of claim 16, the processing circuitry further operable to receive from the O-RU an indication of spatial configurations supported by the O-RU.

17. The network node of any one of claims 15-16, the processing circuitry further operable to transmit to the O-RU an indication of one or more spatial configurations that the O-DU intends to use.

18. The network node of any one of claims 15-17, wherein the spatial configuration comprises an indication of a number of rows and columns in the logical array of logical ports.

19. The network node of claim 18, wherein the spatial configuration further comprises an indication of discrete Fourier transform beam oversampling in each of vertical and horizontal directions for the logical array of logical ports.

20. The network node of any one of claims 15-19, wherein the control plane information further comprises an indication of a codebook type.

21. The network node of any one of claims 15-20, the processing circuitry further operable to receive from the O-RU an indication of codebook types supported by the O-RU.

22. The network node of any one of claims 15-21, the processing circuitry further operable to transmit to the O-RU an indication of one or more codebook types that the O-DU intends to use.

23. The network node of any one of claims 21-22, wherein the codebook type comprises an indication of one or more of a maximum supported rank, a maximum number of channel state information reference signal, CSI-RS, ports, and a maximum number of subbands for the type.

24. The network node of any one of claims 15-23, wherein the codebook description further comprises a wideband part and a subband part.

25. The network node of any one of claims 15-24, wherein each logical port of the array of logical ports is mapped to a disjoint rectangle of antennas in the physical transmit array and wherein the port-to-antenna mapping comprises a single beamforming weight vector and associated beam identifier mapping all logical ports to the physical transmit antenna array.

26. The network node of any one of claims 15-25, wherein the port-to-antenna mapping comprises one beam forming weight tensor for a vertical direction of the physical antenna array and one beam forming weight tensor for a horizontal direction of the physical antenna array.

27. The network node of any one of claims 15-26, wherein the port-to-antenna mapping comprises more than one port-to-antenna mapping each associated with a different frequency range.

28. The network node of any of one of claims 15-27, wherein the control plane information further comprises any one or more of: a power scaling parameter; a tapering parameter; signal quality information; and an indication of a pre-precoder.

29. A method performed by an open radio access network, O-RAN, radio unit, O-RU, for codebook-based dynamic beamforming, the method comprising: receiving (1410), from an O-RAN distributed unit, O-DU, control plane information comprising: a port-to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports; receiving (1412) user plane information from the O-DU for transmission to a wireless device; generating (1414) a beamforming weight matrix for the wireless device based on the port- to-antenna mapping, codebook description, and spatial configuration; and transmitting (1416) the user plane information to the wireless device according to the generated beamforming weight matrix.

30. The method of claim 29, further comprising transmitting (1402) to the O-DU an indication of spatial configurations supported by the O-RU.

31. The method of any one of claims 29-30, further comprising receiving (1404) from the O-DU an indication of one or more spatial configurations that the O-DU intends to use.

32. The method of any one of claims 29-31, wherein the spatial configuration comprises an indication of a number of rows and columns in the logical array of logical ports.

33. The method of claim 32, wherein the spatial configuration further comprises an indication of discrete Fourier transform beam oversampling in each of vertical and horizontal directions for the logical array of logical ports.

34. The method of any one of claims 29-33, wherein the control plane information further comprises an indication of a codebook type.

35. The method of any one of claims 29-34, further comprising transmitting (1406) to the O-DU an indication of codebook types supported by the O-RU.

36. The method of any one of claims 29-35, further comprising receiving (1408) from the O-DU an indication of one or more codebook types that the O-DU intends to use.

37. The method of any one of claims 34-36, wherein the codebook type comprises an indication of one or more of a maximum supported rank, a maximum number of channel state information reference signal, CSI-RS, ports, and a maximum number of subbands for the type.

38. The method of any one of claims 29-37, wherein the codebook description further comprises a wideband part and a subband part.

39. The method of any one of claims 29-38, wherein each logical port of the array of logical ports is mapped to a disjoint rectangle of antennas in the physical transmit array and wherein the port-to-antenna mapping comprises a single beamforming weight vector and associated beam identifier mapping all logical ports to the physical transmit antenna array.

40. The method of any one of claims 29-39, wherein the port-to-antenna mapping comprises one beam forming weight tensor for a vertical direction of the physical antenna array and one beam forming weight tensor for a horizontal direction of the physical antenna array.

41. The method of any one of claims 29-40, wherein the port-to-antenna mapping comprises more than one port-to-antenna mapping each associated with a different frequency range.

42. The method of any of one of claims 29-41, wherein the control plane information further comprises any one or more of: a power scaling parameter; a tapering parameter; signal quality information; and an indication of a pre-precoder.

43. An open radio access network, O-RAN, radio unit, O-RU, network node (300) capable of codebook-based dynamic beamforming, the network node comprising processing circuitry (302) configured to: receive, from an O-RAN distributed unit, O-DU, control plane information comprising: a port-to-antenna mapping that maps logical ports to a physical transmit antenna array of the O-RU; a codebook description describing a codebook for beamforming one or more user layers based on a dual polarized antenna array; and a spatial configuration for a logical array of the logical ports; receive user plane information from the O-DU for transmission to a wireless device; generate a beamforming weight matrix for the wireless device based on the port-to-antenna mapping, codebook description, and spatial configuration; and transmit the user plane information to the wireless device according to the generated beamforming weight matrix.

44. The network node of claim 43, the processing circuitry further operable to transmit to the O-DU an indication of spatial configurations supported by the O-RU.

45. The network node of any one of claims 43-44, the processing circuitry further operable to receive from the O-DU an indication of one or more spatial configurations that the O-DU intendsto use.

46. The network node of any one of claims 43-45, wherein the spatial configuration comprises an indication of a number of rows and columns in the logical array of logical ports.

47. The network node of claim 46, wherein the spatial configuration further comprises an indication of discrete Fourier transform beam oversampling in each of vertical and horizontal directions for the logical array of logical ports.

48. The network node of any one of claims 43-47, wherein the control plane information further comprises an indication of a codebook type.

49. The network node of any one of claims 43-48, the processing circuitry further operable to transmit to the O-DU an indication of codebook types supported by the O-RU.

50. The network node of any one of claims 43-49, the processing circuitry further operable to receive from the O-DU an indication of one or more codebook types that the O-DU intends to use.

51. The network node of any one of claims 48-50, wherein the codebook type comprises an indication of one or more of a maximum supported rank, a maximum number of channel state information reference signal, CSI-RS, ports, and a maximum number of subbands for the type.

52. The network node of any one of claims 43-51, wherein the codebook description further comprises a wideband part and a subband part.

53. The network node of any one of claims 43-52, wherein each logical port of the array of logical ports is mapped to a disjoint rectangle of antennas in the physical transmit array and wherein the port-to-antenna mapping comprises a single beamforming weight vector and associated beam identifier mapping all logical ports to the physical transmit antenna array.

54. The network node of any one of claims 43-53, wherein the port-to-antenna mapping comprises one beam forming weight tensor for a vertical direction of the physical antenna array and one beam forming weight tensor for a horizontal direction of the physical antenna array.

55. The network node of any one of claims 43-54, wherein the port-to-antenna mapping comprises more than one port-to-antenna mapping each associated with a different frequency range.

56. The network node of any of one of claims 43-55, wherein the control plane information further comprises any one or more of: a power scaling parameter; a tapering parameter; signal quality information; and an indication of a pre-precoder.

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