Report configuration for channel state information feedback

Abstract

According to some embodiments, a method performed by a wireless device comprises receiving a channel state information (CSI) configuration comprising antenna port associations. Each of the antenna port associations is between a first set of CSI reference signal (CSI-RS) ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting. A number of CSI-RS ports in the first set is less than in the second set. The method further comprises: receiving a request for a CSI report; performing channel measurements on the first set of CSI-RS ports according to a selected antenna port association; computing CSI for the second set of CSI-RS ports according to the selected antenna port association and the channel measurements on the first set of CSI-RS ports; and reporting the computed CSI to the network node.

Description

REPORT CONFIGURATION FOR CHANNEL STATE INFORMATION FEEDBACK TECHNICAL FIELD

[0001] Embodiments of the present disclosure are directed to wireless communications and,more particularly, to report configuration for channel state information (CSI) feedback. BACKGROUND

[0002] Generally, all terms used herein are to be interpreted according to their ordinarymeaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description.

[0003] Multi-antenna techniques can significantly increase the data rates and reliability of awireless communication system. The performance is improved if both the transmitter and the receiver are equipped with multiple antennas, which results in a multiple-input multiple-output (MIMO) communication channel. Such systems and / or related techniques are commonly referred to as MIMO systems.

[0004] A core component of New Radio (NR) is the support of MIMO related techniques. NRsupports up to 8-layer spatial multiplexing for up to 32 transmit antenna ports at the gNB with channel dependent precoding.

[0005] FIGURE 1 shows an example of data transmission with spatial multiplexing where theinformation carrying symbol vector ^^ = [^^1, ^^2, … , ^^^^]^^is first multiplied (or precoded) by aprecoding matrix ^^ ∈ ^^^^^^×^^ before being sent over NT antenna ports. Each symbol in s isassociated to a data layer and r is the number of data layers or rank, which is a property of the wireless channel between the transmitter and the receiver. ^^ serves to beamform each dataP110844WO01 PCT APPLICATION 2 of 44 layer towards a user equipment (UE) such that signal to interference plus noise ratio (SINR) is maximized and cross layer interference is minimized at the UE receiver. Spatial multiplexing is achieved because multiple symbols can be transmitted simultaneously in a same time and frequency resource element (RE).

[0006] The received NR x 1 signal vector ^^ at the UE quipped with NR receive antennas can beexpressed as ^^ = ^^^^^^ + ^^

[0007] where ^^ ∈ ^^^^^^×^^^^ is the MIMO channel between the transmit and receive antennas, and e isa noise plus interference vector due to receiver noise and interference.

[0008] The precoder matrix ^^ is chosen to match the characteristics of the NRxNT MIMOchannel matrix ^^ resulting in channel dependent precoding. The precoder ^^ can be a wideband precoder, i.e., the same over a whole bandwidth, or a subband precoder, i.e., optimized per subband. ^^ is typically selected from a codebook of precoding matrices by the UE and reportedto the gNB in terms of a precoding matrix indicator (PMI).

[0009] One example method for a UE to select a precoder matrix ^^ can be to select the ^^^^from a codebook that maximizes the Frobenius norm of the hypothesized equivalent channel: max‖^^‖2

[0010] ^^ ^^^^ ^^where ^^ is a channel estimate and ^^^^is a hypothesized precoder matrix with index k.

[0011] In addition to ^^ feedback, a UE typically also feedsback a rank indicator (RI) andchannel quality indicator(s) (CQI) as part of channel state information (CSI) feedback. Given the CSI feedback from the UE, the gNB can determine the transmission parameters to use for data transmissions to the UE.

[0012] For channel estimation purpose, a channel state information reference signal (CSI-RS)is typically transmitted to the UE.

[0013] The antennas with NT antenna ports described above can be either a linear antenna arrayor two-dimensional (2D) plenary antenna array. A linear antenna array is a special case of a 2D antenna array. A 2D antenna array can be described by ^^ℎcolumns, corresponding to the horizontal dimension, ^^^^rows, corresponding to the vertical dimension, and ^^^^polarizations.The total number of antenna ports is thus ^^ = ^^ℎ^^^^^^^^. An example of a cross polarized (i.e.,^^^^ = 2) antenna array with (^^ℎ,^^^^) = (4,4) is illustrated in FIGURE 2.P110844WO01 PCT APPLICATION 3 of 44

[0014] FIGURE 2 illustrates a two-dimensional antenna array of cross-polarized antennaelements (^^^^ = 2), with ^^ℎ = 4 horizontal antenna elements and ^^^^ = 4 vertical antennaelements. The 2D antenna array may be rotated at any angle. In this case, the row and columns may no longer correspond to vertical and horizontal directions. To reflect this more general case in NR, a 2D antenna array is simply defined by a number of antenna ports in each of twodimensions, i.e., ^^1 and ^^2, and ^^^^ is always 2. Thus, the total number of antenna ports is ^^ =2^^1^^2.

[0015] The concept of an antenna port is non-limiting in the sense that it can refer to anyvirtualization (e.g., linear mapping) of the physical antenna elements. For example, pairs of physical sub-elements could be fed the same signal, and thus share the same virtualized antenna port.

[0016] In NR, for downlink channel measurement by a UE, a reference signal is transmitted ateach antenna port. The reference signal is referred to as non-zero power channel state information reference signal (NZP CSI-RS). NZP CSI-RS is configured in terms of NZP CSI- RS resources. For simplicity, “NZP” may be omitted in the following disclosure. A NZP CSI- RS resource supports up to 32 antenna ports. The antenna ports are also referred to as CSI-RS antenna ports, CSI-RS ports, or antenna ports. Different CSI-RS antenna ports in a CSI-RS resource are allocated with different REs and / or different CDM (code division multiplexing) codes so that the downlink channel associated to each antenna port can be individually measured and estimated.

[0017] Three densities are supported, i.e., ^^ = ½, 1, and 3. ^^ is the number of REs per RB perCSI-RS port. The parameter ^^ = ½ means one RE per port in every other RBs, e.g., in even orodd numbered RBs. ^^ = 3 is only supported for single port CSI-RS resource.

[0018] In a CSI-RS resource, there can be multiple CDM groups. A CDM group consists of 2,4 or 8 REs, corresponding to length ^^ = 2, 4, or 8 CDM codes, respectively. The CDM codesused can be either length 2 or length 4 time domain orthogonal cover codes (TD-OCC), i.e., TD-OCC2 or TD-OCC4, or length 2 frequency domain OCC (FD-OCC), i.e., FD-OCC2, or both TD-OCC and FD-OCC. The CDM groups are numbered in order of increasing frequency domain allocation first and then increasing time domain allocation. An example of a CSI-RS resource for 32 antenna ports are shown in FIGURE 3, where CSI-RS REs in one RB is shown.P110844WO01 PCT APPLICATION 4 of 44

[0019] FIGURE 3 illustrates an example of a CSI-RS resource for 32 antenna ports with 8CDM groups. In this case, there are 8 CDM groups each with 4 REs. The CDM codes are TD- OCC2 plus FD-OCC2.

[0020] Each antenna port is mapped to one of the CDM groups. Antenna ports are mapped inCDM group first, then frequency, and then time. Within each CDM group, antenna ports are multiplexed via CDM codes or sequences. CSI-RS antenna ports are numbered according to ^^ = 3000 + ^^ + ^^^^;^^ = 0,1, ... ,^^⁄ ^^ − 1^^ = 0,1, ... , ^^ − 1;where ^^ is the CDM code index given in^^ ∈ {1,2,4,8} is the CDM groupsize, and ^^ is the number of CSI-RS ports.

[0021] The NR Type I single panel codebook is based on discrete Fourier transform (DFT)beams or precoders and is for cross polarized 2D antenna arrays, where a DFT beam is selected for each MIMO layer. The same DFT beam is applied to antenna ports at both polarizations. A co-phasing factor is applied at antenna ports of one of the two polarizations. The details of Type I single panel codebook can be found in Third Generation Partnership Project (3GPP) TS38.214 V18.1.0 section 5.2.2.2.1.

[0022] For example, for a CSI-RS resource with ^^CSI-RS = 2^^1^^2 antenna ports, rank 1precoding matrix for codebook mode 1 is given by^^ =1 ^^^^,√^^CSI-RS[^^^^^^^^^^,^^], ^^ = 0,1, … ,^^1^^1 − 1; ^^ = 0,1, … ,^^2^^2 − 1.where (^^,^^) and is2^^^^ ^^ by ^^^,^^ = [^^^^ ^^2^^^^(^^1−1)^ ^^ ^^ ^^1^^1^^^^ ... ^^^^1^^1^^^^] and ^^^^= [1 ^^^^ 2^^^^ ^^2^^2 ... ^^^^^^1and ^^2are the factor in the dimension ^^1 and ^^2, respectively. ^^^^ = ^^^^^^^^⁄ 2is a co-phasing factor. The supported (^^1,^^2)and (^^1,^^2) are given in Table2 of 3GPP TS38.214, which is copied below:P110844WO01 PCT APPLICATION 5 of 44 Table 5.2.2.2.1-2: Supported configurations of (^^1,^^2)and (^^1,^^2) Number of CSI-RS antenna ports, ^^(^^^^,^^^^)(^^^^,^^^^)CSI-RS4 (2,1) (4,1)8(2,2) (4,4)(4,1) (4,1)12(3,2) (4,4)(6,1) (4,1)16(4,2) (4,4)(8,1) (4,1)(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)

[0023] A type I single panel codebook based precoding matrix is a two-stage precoder and canbe expressed as ^^ = ^^1^^2 where ^^1 contains the selected DFT beams and ^^2 contains co-1 ^^ ng factors. For the above rank 1 precoding matrix, ^^^^,^^0 1 = √^^CSI-RS[0 ,1 phasi] ^^2 = [^^^^]. DFT beams {^^^^,^^} are also referred to as spatial

[0024] According to 3GPP NR specification, precoded physical downlink shared channel(PDSCH) signals ^^ = [^^1, ^^2, … , ^^^^]^^by ^^ (i.e., ^^^^) are equivalent to corresponding symbols transmitted on the CSI-RS antenna ports 3000, … , 3000 + ^^^^^^^^−^^^^ − 1 as given by^^(3000)^^1⋯= ^^. based ^^ structure mean that the CSI-RS antenna ports for a 2Dports need to be indexed in order of increasing along the ^^2dimension first and then increasing along the ^^1dimension at a first polarization and repeat the above for the other polarization. An example is shown in FIGURE 4 for a 2D antenna with 32 ports where the CSI-RS port number is given by adding 3000 to the numbers shown in the figure.

[0026] FIGURE 4 illustrates an example of a mapping of CSI-RS antenna ports to a 2D antennawith 32 ports.P110844WO01 PCT APPLICATION 6 of 44

[0027] In Rel-18, a network energy saving feature was introduced for muting a subset of CSI-RS ports for energy saving purposes. Consider an NZP CSI-RS resource configured for channelmeasurement with ^^^^^^^^−^^^^ ports. According to this feature, a bitmap with ^^^^^^^^−^^^^ = 2^^1^^2bits are signaled from the network (e.g., gNB) to the UE. The bitmap can have ^^ ports that areunmuted, and the remaining ^^^^^^^^−^^^^ − ^^ ports are muted. Because the network does nottransmit any CSI-RS on the muted ports, the network can save energy by skipping these transmissions on muted ports. In this feature, the number of unmuted ports ^^ have to correspond to one of the number of CSI-RS ports (among 2, 4, 8, 12, 16, 24 and 32) supported in NR.

[0028] For example, when ^^^^^^^^−^^^^ = 32 ports, then the possible values for port muting are^^ ∈ {2, 4, 8, 12, 16, 24}. The reason for this restriction in Rel-18 is that a ^^ port NR Type Isingle panel codebook can be used for CSI calculation / computation at the UE when ^^^^^^^^−^^^^− ^^ ports are muted.

[0029] The port numbering when ^^^^^^^^−^^^^ − ^^ ports are muted is given in 3GPP TS 38.214 as:“Each sub-configuration can be configured with an antenna port subset using the higher layerbitmap parameter [port-subsetIndicator] which contains the bit sequence ^^0,^^1, ... ,^^^^^^−1,where ^^0 is the MSB and ^^^^m−1 is the LSB, bit ^^^^ corresponds to antenna port 3000 + i, and^^m is the number of ports nrofPorts configured for the CSI-RS resources(s) within a NZP- CSI-RS-ResourceSet contained in the CSI-ResourceConfig for channel measurement that corresponds to the CSI-ReportConfig. A bit value 0 in [port-subsetIndicator] indicates that the corresponding antenna port is disabled for the sub-configuration, whereas bit value 1 indicates that the antenna port is enabled and belongs to the antenna port subset for the sub-configuration. For the derivation of PMI, antenna ports corresponding to all bits with value of 1 in [port- subsetIndicator] are mapped to consecutive antenna ports starting at CSI-RS antenna port 3000 in increasing order of the bit position in [port-subsetIndicator].”

[0030] In the 3GPP specification text above, port-subsetIndicator is the port muting bitmapand ^^^^is the notation used instead of ^^^^^^^^−^^^^. As per the last sentence in the above 3GPP specification text, all the unmuted ports (i.e., those with bits corresponding to value 1 in the bitmap) are mapped to consecutive antenna ports.

[0031] An example is shown in FIGURE 5 for a 2D antenna with 32 ports where 8 of the portsare muted. The CSI-RS port number is this example is given by adding 3000 to the numbers shown in the figure.P110844WO01 PCT APPLICATION 7 of 44

[0032] FIGURE 5 illustrates an example of a mapping of CSI-RS antenna ports to a 2D antennawith 32 ports with 8 ports muted.

[0033] According to 3GPP TS 38.214 V18.1.0, precoded PDSCH signals ^^ = [^^1, ^^2, … , ^^^^]^^ by ^^ (i.e., ^^^^) are equivalent to corresponding symbols transmitted on the^^(3000)^^1ports 3000, … , 3000 + ^^ − 1 as⋯= ^^.

[0034] The above is based on theports are given consecutivesindices.

[0035] Artificial Intelligence (AI) and Machine Learning (ML) have been investigated, bothin academia and industry, as promising tools to optimize the design of the air-interface in wireless communication networks. Example use cases include using autoencoders for channel state information (CSI) compression to reduce the feedback overhead and improve channel prediction accuracy; using deep neural networks for classifying line-of-sight (LOS) and non- LOS (NLOS) conditions to enhance the positioning accuracy; using reinforcement learning for beam selection at the network side and / or the UE side to reduce the signaling overhead and beam alignment latency; and using deep reinforcement learning to learn an optimal precoding policy for complex MIMO precoding problems.

[0036] In 3GPP NR standardization work, a release 18 study item on AI / ML for the NR airinterface explored the benefits of augmenting the air-interface with features enabling improved support of AI / ML based algorithms for enhanced performance and / or reduced complexity / overhead. Through studying a few selected use cases (CSI feedback, beam management, and positioning), the study item lays a foundation for future air-interface use cases leveraging AI / ML techniques.

[0037] Terminologies such as AI / ML model, AI / ML model inference (which is henceforthreferred to as inference), AI / ML model training (which is henceforth referred to as training), data collection, and model monitoring are defined in Section 3.1 of 3GPP TR38.843 V18.0.0.

[0038] Two AI CSI use cases were studied in 3GPP Rel-18, and they are under continued studyin 3GPP Rel-19.

[0039] One CSI prediction use case uses one or more one-sided UE-sided models, where themodel inference is performed entirely at the UE. One or more AI / ML models can be trained and deployed at a UE for the AI-based CSI-prediction feature. During model inference, a UEP110844WO01 PCT APPLICATION 8 of 44 is configured by the gNB to measure a set of historical CSI-RSs and then report a predicted CSI for one or multiple future time instances using its AI / ML model(s). FIGURE 6 illustrates an example for the inference procedure for CSI prediction. For generating the input of CSI prediction model, it may need some further pre-processing on the measured channel. For the output of the CSI prediction model, some further post-processing may also be applied.

[0040] FIGURE 6 illustrates an example of CSI prediction using UE-side AI model(s).

[0041] Another use case is the CSI compressing use case using one or more two-sided AI / MLmodels. A two-sided AI / ML model refers to a paired AI / ML Model(s) over which joint inference is performed across the UE and the network, i.e., the first part of the inference is firstly performed by UE and then the remaining part is performed by gNB, or vice versa. As an example, FIGURE 7 shows the autoencoder (AE)-based CSI compression, where an encoder (UE-part of the two-sided AE model) is operated at a UE to compress the estimated wireless channel, and the output of the encoder (the compressed wireless channel information estimates) is reported from the UE to a gNB. The gNB uses a decoder (network part of the two-sided AE model) to reconstruct the estimated wireless channel information. Here the two-sided AI / ML model is composed of the encoder at the UE side and the decoder at the base station (i.e., a gNB) side. Note that in the case of a two-sided model, the code is generated by the encoder and only interpretable by a jointly trained decoder. The situation is different from running an AI / ML model in the UE, reporting the output over the air in a fully standardized format, and running a separate AI / ML model at the base station.

[0042] FIGURE 7 illustrates an autoencoder (AE)-based CSI compression using two-sidedAI / ML model use case.

[0043] There currently exist certain challenges. For example, as the number of antenna portsincreases, CSI acquisition for codebook-based downlink transmission becomes more and more challenging. One problem is large downlink reference signal (RS) overhead.

[0044] For example, in Rel-19 NR, up to 128 CSI-RS ports are supported, which can be usedfor a network with 128 active antenna ports (see Objective 2 in RP-234007, New WID: NR MIMO Phase 5, 3GPP RAN Meeting #102, Edinburgh, Scotland, December 11-15, 2023). Sounding downlink RS for so many ports introduces significant overhead, leaving less time- frequency resources for actual data transmission. Thus, how to obtain accurate CSI with reduced DL-RS overhead for downlink codebook-based transmission is a problem to solve.P110844WO01 PCT APPLICATION 9 of 44 SUMMARY

[0045] As described above, certain challenges currently exist with channel state information(CSI) acquisition for codebook-based downlink transmission. Certain aspects of the present disclosure and their embodiments may provide solutions to these or other challenges. For example, particular embodiments include configuring a user equipment (UE) to report CSI computation / estimates / prediction associated to ^^^^antenna ports, based on the channel measurements on ^^^^^^antenna ports, where the ^^^^^^antenna ports are a subset of the ^^^^antenna ports.

[0046] According to particular embodiments, a method at a UE comprises receivingconfiguration of a CSI reporting configuration from a network node. Receiving the configuration comprises one or more of the following: receiving at least one association between ^^^^^^antenna ports to be used for channel measurements and ^^^^antenna ports to be used for CSI computation / estimation / prediction; receiving channel measurement resource(s) with ^^^^^^antenna ports that are to be used by the UE to perform channel measurements, and receiving information on ^^^^antenna ports that are to be used by the UE for CSI computation / estimates / prediction based on channel measurements performed on the channelmeasurement resource(s) with ^^^^^^ antenna, where ^^^^ > ^^^^^^; and, reportingcomputed / estimated / predicted CSI corresponding to ^^^^antenna ports to the network node.

[0047] An example of the CSI is entries from a defined precoding matrix indication (PMI)codebook for ^^^^antenna ports in the specifications.

[0048] According to some embodiments, a method is performed by a wireless device. Themethod comprises receiving from a network node a CSI configuration. The CSI configuration comprises one or more antenna port associations, wherein each of the one or more antenna port associations is between a first set of CSI-RS ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting. A number of CSI-RS ports in the first set (e.g., ^^^^) is less than a number of CSI-RS ports in the second set (e.g., ^^^^^^). The method further comprises: receiving a request from the network node for a CSI report; performing channel measurements on the first set of CSI-RS ports according to a selected antenna port association of the one or more antenna port associations; computing CSI for the second set of CSI-RS ports according to the selected antenna port association and the channel measurements on the first set of CSI-RS ports; and reporting the computed CSI to the network node in a CSI report.P110844WO01 PCT APPLICATION 10 of 44

[0049] In particular embodiments, the computed CSI comprises a channel quality indicator,CQI, where the CQI is computed by the wireless device assuming precoded physical downlink shared channel, PDSCH, signals are equivalent to corresponding symbols transmitted on the second set of CSI-RS ports.

[0050] In particular embodiments, the antenna port association comprises a bitmapcorresponding to each port of the second set of antenna ports. The bitmap indicates unmuted ports that correspond to the ports in the first set of CSI-RS ports.

[0051] In particular embodiments, receiving the CSI configuration comprises receiving a radioresource control (RRC) configuration message.

[0052] In particular embodiments, the selected antenna port association is based on anindication in the CSI configuration or in the request for the CSI report.

[0053] In particular embodiments, the one or more antenna port associations are part of a CSIresource configuration or a CSI reporting configuration.

[0054] In particular embodiments, the request for a CSI report comprises an uplink relateddownlink control information.

[0055] In particular embodiments, the number of CSI-RS ports in the second set is equal to afull set of antenna ports. In particular embodiments, the number of CSI-RS ports in the second set is less than a full set of antenna ports. Each of the one or more antenna port associations may comprise a second association between each of the second set of CSI-RS ports used for CSI reporting and the full set of antenna ports.

[0056] In particular embodiments, computing CSI for the second set of CSI-RS portscomprises interpolating measurements based on the channel measurements on the first set of CSI-RS ports. In particular embodiments, computing CSI for the second set of CSI-RS ports is based on output of a machine learning model whose input is based on the channel measurements on the first set of CSI-RS ports.

[0057] In particular embodiments, the method further comprises reporting a capability of thewireless device for computing CSI according to one or more of a number of CSI-RS ports in the first set, a number of CSI-RS ports in the second set, and a maximum number of interpolated CSI-RS ports. The capability of the wireless device for computing CSI may comprise a capability of the wireless device for computing CSI according to a first number of ports in a first dimension and a second number of ports in a second dimension.P110844WO01 PCT APPLICATION 11 of 44

[0058] In particular embodiments, the method further comprises determining an accuracy ofthe computed CSI for the second set of CSI-RS ports based on a comparison of computed CSI for the second set of CSI-RS ports and actual channel measurements on the second set of CSI- RS ports.

[0059] According to some embodiments, a wireless device comprises processing circuitryoperable to perform any of the methods of the wireless device described above.

[0060] 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 wireless device described above.

[0061] According to some embodiments, a method is performed by a network node. Themethod comprises transmitting to a wireless device a CSI configuration. The CSI configuration comprises one or more antenna port associations. Each of the one or more antenna port associations is between a first set of CSI-RS ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting. A number of CSI-RS ports in the first set is less than a number of CSI-RS ports in the second set. The method further comprises: transmitting a request to the wireless device for a CSI report; transmitting CSI-RS on the first set of CSI- RS ports; and receiving computed CSI for the second set of CSI-RS ports from the wireless device in a CSI report.

[0062] In particular embodiments, transmitting the CSI configuration comprises transmittinga RRC configuration message.

[0063] In particular embodiments, the method further comprises receiving a capability of thewireless device for computing CSI according to one or more of a number of CSI-RS ports in the first set, a number of CSI-RS ports in the second set, and a maximum number of interpolated CSI-RS ports. The capability of the wireless device for computing CSI may comprise a capability of the wireless device for computing CSI according to a first number of ports in a first dimension and a second number of ports in a second dimension.

[0064] According to some embodiments, a network node comprises processing circuitryoperable to perform any of the network node methods described above.

[0065] Another computer program product comprises a non-transitory computer readablemedium storing computer readable program code, the computer readable program codeP110844WO01 PCT APPLICATION 12 of 44 operable, when executed by processing circuitry to perform any of the methods performed by the network node described above.

[0066] Certain embodiments may provide one or more of the following technical advantages.For example, in particular embodiments CSI corresponding to a large number of antenna ports may be acquired at the network side by only transmitting CSI-RS on a subset of the antenna ports. Thus, more resources may be freed up for downlink data transmissions. 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 shows an example of data transmission with spatial multiplexing where the information carrying symbol vector is first multiplied (or precoded) by a precoding matrix; FIGURE 2 illustrates a two-dimensional antenna array of cross-polarized antenna elements; FIGURE 3 illustrates an example of a channel state information reference signal (CSI- RS) resource for 32 antenna ports with 8 code division multiplexing (CDM) groups; FIGURE 4 illustrates an example of a mapping of CSI-RS antenna ports to a two- dimensional antenna with 32 ports; FIGURE 5 illustrates an example of a mapping of CSI-RS antenna ports to a two- dimensional antenna with 32 ports with 8 ports muted; FIGURE 6 illustrates an example of CSI prediction using user equipment (UE)-side artificial intelligence (AI) model(s); FIGURE 7 illustrates an autoencoder (AE)-based CSI compression using two-sided AI / ML model use case; FIGURE 8 is a flowchart illustrating steps of particular embodiments; FIGURE 9 illustrates an example antenna layout; FIGURE 10 illustrates an example of antenna layouts with irregular patterns; FIGURE 11 illustrates an example communication system, according to certain embodiments;P110844WO01 PCT APPLICATION 13 of 44 FIGURE 12 illustrates an example user equipment (UE), according to certain embodiments; FIGURE 13 illustrates an example network node, according to certain embodiments; FIGURE 14 illustrates a method performed by a wireless device, according to certain embodiments; and FIGURE 15 illustrates a method performed by a network node, according to certain embodiments. DETAILED DESCRIPTION

[0068] As described above, certain challenges currently exist with channel state information(CSI) acquisition for codebook-based downlink transmission. Certain aspects of the present disclosure and their embodiments may provide solutions to these or other challenges. For example, particular embodiments include configuring a user equipment (UE) to report CSI computation / estimates / prediction associated to ^^^^antenna ports, based on the channel measurements on ^^^^^^antenna ports, where the ^^^^^^antenna ports are a subset of the ^^^^antenna ports.

[0069] Particular embodiments are described more fully with reference to the accompanyingdrawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0070] An example flowchart of the steps involved in particular embodiments is shown inFIGURE 8. Some steps shown in the example flowchart may be optional, and the steps shown in the example flowchart may in some cases be performed in different orders.

[0071] In Step 101, a UE receives configuration from a network node (e.g., a gNB) for CSIreporting (e.g., a CSI reporting configuration) and CSI channel measurement resources and / or interference resources.

[0072] In an embodiment, the CSI channel measurement resource(s) (e.g., NZP CSI-RSresources) are configured with ^^^^^^antenna ports, and the CSI report is configured for ^^^^antenna ports, where ^^^^ > ^^^^^^. That is, the UE is configured to report CSI for ^^^^ antennaports, by measuring only on a subset of the antenna ports.P110844WO01 PCT APPLICATION 14 of 44

[0073] The association between the ^^^^^^ antenna ports (for channel measurements) and the ^^^^antenna ports (for CSI reporting) is configured by the network.

[0074] In an embodiment, the antenna port association (i.e., the association between the portsfor channel measurements and the ports for CSI reporting) is configured from the network to the UE by using a CSI-RS port subset indicator pattern. As an example, the CSI-RS port subset indicator pattern is a bit string with a size of ^^^^. In the bit string, each bit corresponds to an antenna port. When a bit is set to 1, the corresponding port is unmuted and is measured by the UE for computing / estimating / predicting a CSI; when a bit is set to zero, the corresponding port is muted and is not measured by the UE, but the UE shall compute / estimate / predict the CSI using this corresponding port.

[0075] As part of the CSI reporting configuration, the UE may receive from the network nodeone or more CSI-RS port subset indicator pattern(s), e.g., multiple ^^^^^^antenna ports configurations for CSI measurements are associated to the same set of ^^^^ports for CSI reporting. For example, multiple length ^^^^bit strings may be configured to the UE wherein a different number ^^^^^^antenna ports may be unmuted in each of the multiple length ^^^^bit strings.

[0076] In some embodiments, the CSI-RS port subset indicator pattern(s) may be configuredby the network node to the UE via one or more CSI-ReportSubConfiguration information element (IE) as specified in 3GPP TS 38.331 V18.0.0. In one embodiment, the CSI-RS port subset indicator pattern(s) are configured as part of CSI resource configuration. In another embodiment, the CSI-RS port subset indicator pattern(s) may be configured as part of either NZP-CSI-RS-ResourceSet IE or NZP-CSI-RS-Resource IE where these IEs are specified as part of 3GPP TS 38.331. In yet another embodiment, a new IE CSI-ResourceSubConfig is introduced into 3GPP specifications (e.g., 3GPP TS 38.331) that contains the CSI-RS port subset indicator pattern(s).

[0077] In another embodiment, one or more CSI-RS port subset indicator pattern(s) may beconfigured as part of the CSI reporting configuration by the network node to the UE via one or more CSI-ReportSubConfiguration IEs wherein each of the CSI-ReportSubConfiguration is associated with a CSI-ReportSubConfigId. A subset of the of these CSI-RS port subset indicator pattern(s) may be configured as part of CSI-AssociatedReportConfigInfo field in CSI- AperiodicTriggerStateList IE as specified in 3GPP TS 38.331.P110844WO01 PCT APPLICATION 15 of 44

[0078] In another embodiment, one or more CSI-RS port subset indicator pattern(s) may beconfigured as part of the CSI reporting configuration by the network node to the UE via one or more CSI-ReportSubConfiguration IEs wherein each of the CSI-ReportSubConfiguration is associated with a CSI-ReportSubConfigId. A subset of the of these CSI-RS port subset indicator pattern(s) may be configured as part of CSI-SemiPersistentOnPUSCH-TriggerState field in CSI-SemiPersistentOnPUSCH-TriggerStateList IE as specified in 3GPP TS 38.331.

[0079] In another embodiment, the antenna port association is configured by using two CSI-RS port subset indicator patterns. As an example, a network node supports ^^^^antenna ports, but it decides to only enable ^^^^antenna ports for data transmission to save energy. Further, to reduce the CSI-RS transmission overhead and CSI-RS resource overhead, the network nodedecides to only transmit CSI-RS on ^^^^^^ antenna ports for CSI measurements. Here, ^^^^ ≥ ^^^^ ≥^^^^^^. In this case, a first CSI-RS port subset indicator pattern may be used to indicate which antenna ports are muted for both CSI-RS and physical downlink shared channel (PDSCH) transmission, and the second CSI-RS port subset indicator pattern may be used to indicate which antenna ports are muted for CSI-RS transmission but still used for PDSCH transmission.

[0080] In an embodiment, the antenna port association (i.e., the association between the portsfor CSI measurements and the ports for CSI reporting) are indicated in a RRC message.

[0081] In one embodiment, regardless of the enabled antenna port patterns for the CSI-RSmeasurement resources (e.g., the ^^^^^^antenna ports configured for the NZP CSI-RS resources),the UE shall always assume that the precoded PDSCH signals ^^ = [^^1, ^^2, … , ^^^^]^^by ^^ (i.e., ^^^^) are equivalent to corresponding symbols transmitted on the CSI-RS antenna ports ^^(3000)^^13000, … , 3000 + ^^^^ − 1 as given by⋯= ^^.

[0082] All the ^^^^ ports are used foronly a subset of theports (^^^^^^antenna ports) are enabled for CSI measurement and reporting. This is different from Rel-18 energy saving feature where only the unmuted ports are used for PDSCH transmission.

[0083] In Step 102, the UE receives a request from the network node for CSI report based onone or more of antenna port associations (i.e., the association between the ports for channel measurements and the ports for CSI reporting).P110844WO01 PCT APPLICATION 16 of 44

[0084] The request may be received via an uplink related downlink control information (DCI)that requests the CSI report. The uplink DCI also indicates one or more of antenna port associations. To simplify the description herein, assume that the indicated antenna port association is X.

[0085] In one embodiment, when a ‘CSI request field’ in uplink DCI indicates a codepoint thattriggers an aperiodic trigger state that is associated with one or more CSI- AssociatedReportConfigInfo fields (as described under Step 101), then the CSI-RS port subset indicator pattern(s) configured as part of the CSI-AssociatedReportConfigInfo fields are indicated to the UE (note that these indicated CSI-RS port subset indicator pattern(s) are referred to as the indicated one or mor antenna port associations above).

[0086] In another embodiment, when a ‘CSI request field’ in uplink DCI indicates a codepointthat triggers a CSI-SemiPersistentOnPUSCH-TriggerState field (as described under Step 101), then the CSI-RS port subset indicator pattern(s) configured as part of the CSI- SemiPersistentOnPUSCH-TriggerState field are indicated to the UE (note that these indicated CSI-RS port subset indicator pattern(s) are referred to as the indicated one or more antenna port associations above).

[0087] In Step 103, UE performs channel measurements on the enabled / unmuted ^^^^^^ antennaports, based on the received antenna port association indicator X.

[0088] In Step 104, UE computes a CSI report for ^^^^ antenna ports according to the receivedantenna port association indicator X.

[0089] In an example, the ^^^^ antenna ports enabled for PDSCH transmission have a uniformantenna array layout, in addition, the enabled ^^^^^^antenna ports are configured such that it performs uniform sampling of ^^^^antenna ports. FIGURE 9 illustrates an example antenna layout. In this case, if the layout of the ^^^^^^antenna ports and the ^^^^antenna ports are indicated to the UE, then the UE may perform “port interpolation” among the measurements for ^^^^^^antenna ports to generate an estimated / predicted CSI for the ^^^^antenna ports. The legacy PMI codebook (e.g., a NR Type I single panel codebook) may be reused for the CSI report.

[0090] FIGURE 9 illustrates an example of uniform array layout with 8 out of 16 enabled portsthat allows for interpolation by the UE to report a legacy PMI codebook.

[0091] In another example, the ^^^^ antenna ports enabled for PDSCH transmission have anirregular array pattern, and / or the enabled ^^^^^^antenna ports have an irregular array pattern, see FIGURE 10, such that it is difficult for the UE to use simple interpolation algorithms toP110844WO01 PCT APPLICATION 17 of 44 compute an estimated / predicted CSI for the ^^^^antenna ports. In addition, the legacy PMI codebook may not work for this array setup. In this case, an AI model may be trained for the UE to calculate / generate a CSI report, e.g. by using port interpolation where the channel estimates for the muted ports are prediction using an AI model.

[0092] FIGURE 10 illustrates an example of antenna layouts with irregular patterns.

[0093] In one embodiment, a UE measures CSI-RS(s) of multiple different ^^^^^^ number, eachwith corresponding subsetIndicator pattern, and computes CSI(s) for the selected ^^^^^^according to certain criteria. For example, the one(s) with highest channel quality indicator (CQI), the one(s) with certain CQI range, the one(s) with highest number of layers, the one(s) with certain number of layers, or the one(s) with equivalent or slightly different PDSCH throughput as using ^^^^.

[0094] In Step 105, the UE reports the computed CSI report for the ^^^^ antenna ports to thenetwork node. In one embodiment, the report may contain only one index or indexes associated with the selected ^^^^^^(s).

[0095] Although the above embodiments are explained using NZP CSI-RS, in 6G or beyond,other types of reference signals may also be used.

[0096] In some embodiments, it is observed that the UE’s AI / ML model ability to accuratelyperform port interpolation where the channel estimate for the muted ports is predicted or estimated (or equivalently compute a PMI without knowledge of the channel estimate of all antenna ports configured for the PMI codebook) may vary between different UEs. Thus, the UE may in its capabilities indicate the degree of supported port interpolation.

[0097] As an example, the UE may report a maximum number of interpolated ports Q1 in firstdimension (corresponding to N1) and Q2 in the second dimension (corresponding to N2). If the UE report Q1=1 to the network, then the UE can perform port interpolation of one muted port in the first dimension and so on.

[0098] To support the pattern in FIGURE 9, then the UE may report to the network a capabilityof at least Q1=2. To support the pattern in FIGURE 10 left, then the UE may report the capability of Q1=2, Q2=1.

[0099] Thus, the UE may report one or more multiples of the (Q1,Q2) to the network.

[0100] The network may trigger a performance monitoring report from the UE, where all^^^^ = ^^^^^^ antenna (CSI-RS) ports are intermittently (e.g., aperiodically) transmitted. The UEmay then estimate the performance of its configured ^^^^^^ < ^^^^ based AI / ML prediction.P110844WO01 PCT APPLICATION 18 of 44

[0101] The UE may then report the performance of current configured port muting pattern tothe network using a defined and specified metric.

[0102] After this, the UE may be requested by the network to report a new UE capability wherethe UE supported values of (Q1,Q2) may have changed based on the updated model performance estimate.

[0103] FIGURE 11 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.

[0104] 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.

[0105] 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.P110844WO01 PCT APPLICATION 19 of 44

[0106] 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).

[0107] The host 116 may be under the ownership or control of a service provider other than anoperator 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.

[0108] As a whole, the communication system 100 of FIGURE 11 enables connectivitybetween the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave AccessP110844WO01 PCT APPLICATION 20 of 44 (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0109] In some examples, the telecommunication network 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 are connected to the telecommunication network 102. For example, the telecommunications network 102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive IoT services to yet further UEs.

[0110] 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).

[0111] 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 hubP110844WO01 PCT APPLICATION 21 of 44 114 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.

[0112] 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 still connected via the hub 114 via a wired or wireless connection. In some embodiments, the hub 114 may be a dedicated hub – that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 110b. In other embodiments, the hub 114 may be a non-dedicated hub – that is, a device which is capable of operating to route communications between the UEs and network node 110b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0113] FIGURE 12 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.

[0114] 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 ofP110844WO01 PCT APPLICATION 22 of 44 a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0115] The UE 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 12. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0116] The processing circuitry 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 be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 202 may include multiple central processing units (CPUs).

[0117] In the example, the input / output interface 206 may be configured to provide an interfaceor 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 forceP110844WO01 PCT APPLICATION 23 of 44 sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0118] In some embodiments, the power source 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.

[0119] 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 other application, and corresponding data 216. The memory 210 may store, for use by the UE 200, any of a variety of various operating systems or combinations of operating systems.

[0120] 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 andP110844WO01 PCT APPLICATION 24 of 44 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.

[0121] 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.

[0122] 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.

[0123] 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 severalP110844WO01 PCT APPLICATION 25 of 44 sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0124] As another example, a UE comprises an actuator, a motor, or a switch, related to 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.

[0125] 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 12.

[0126] 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 case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or otherP110844WO01 PCT APPLICATION 26 of 44 equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0127] In practice, any number of UEs may be used together with respect to a single use case.For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE 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.

[0128] FIGURE 13 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)).

[0129] Base stations may be categorized based on the amount of coverage they provide (or,stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units 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).

[0130] 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).P110844WO01 PCT APPLICATION 27 of 44

[0131] 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.

[0132] 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.

[0133] 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.P110844WO01 PCT APPLICATION 28 of 44

[0134] 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 or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 302. The memory 304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 302 and utilized by the network node 300. The memory 304 may be used to store any calculations made by the processing circuitry 302 and / or any data received via the communication interface 306. In some embodiments, the processing circuitry 302 and memory 304 is integrated.

[0135] 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.P110844WO01 PCT APPLICATION 29 of 44

[0136] 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).

[0137] 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-end circuitry 318 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 310 is separate from the network node 300 and connectable to the network node 300 through an interface or port.

[0138] The antenna 310, communication interface 306, and / or the processing circuitry 302 maybe 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.

[0139] 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.P110844WO01 PCT APPLICATION 30 of 44

[0140] Embodiments of the network node 300 may include additional components beyondthose shown in FIGURE 13 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.

[0141] FIGURE 14 is a flowchart illustrating an example method in a wireless device,according to certain embodiments. In particular embodiments, one or more steps of FIGURE 14 may be performed by UE 200 described with respect to FIGURE 12.

[0142] The method may begin at step 1410, where the wireless device (e.g., UE 200) reports acapability of the wireless device for computing CSI according to one or more of a number of CSI-RS ports in the first set, a number of CSI-RS ports in the second set, and a maximum number of interpolated CSI-RS ports. For example, a wireless device’s AI / ML model ability to accurately perform port interpolation may vary between wireless devices. Thus, the wireless may indicate to the network node the degree or level of supported port interpolation.

[0143] The capability of the wireless device for computing CSI may comprise a capability ofthe wireless device for computing CSI according to a first number of ports in a first dimension and a second number of ports in a second dimension.

[0144] The capabilities are described in more detail with respect to the embodiments andexamples described above.

[0145] At step 1412, the wireless device receives from a network node a CSI configuration.The CSI configuration comprises one or more antenna port associations, wherein each of the one or more antenna port associations is between a first set of CSI-RS ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting. A number of CSI-RS ports in the first set (e.g., ^^^^) is less than a number of CSI-RS ports in the second set (e.g., ^^^^^^).

[0146] In particular embodiments, receiving the CSI configuration comprises receiving a RRCconfiguration message. In particular embodiments, the one or more antenna port associations are part of a CSI resource configuration or a CSI reporting configuration.P110844WO01 PCT APPLICATION 31 of 44

[0147] In particular embodiments, the antenna port association comprises a bitmapcorresponding to each port of the second set of antenna ports. The bitmap indicates unmuted ports that correspond to the ports in the first set of CSI-RS ports.

[0148] In particular embodiments, the number of CSI-RS ports in the second set is equal to afull set of antenna ports (e.g., ^^^^). In particular embodiments, the number of CSI-RS ports inthe second set is less than a full set of antenna ports (e.g., ^^^^). Each of the one or more antennaport associations may comprise a second association between each of the second set of CSI- RS ports used for CSI reporting and the full set of antenna ports.

[0149] Additional details are described above with respect to the subset indicator patternsdescribed with respect to particular embodiments and examples. Also refer to step 101 of FIGURE 8.

[0150] At step 1414, the wireless device receives a request from the network node for a CSIreport. In particular embodiments, the request for a CSI report comprises an uplink DCI. Also refer to step 102 of FIGURE 8.

[0151] At step 1416, the wireless device performs channel measurements on the first set ofCSI-RS ports according to a selected antenna port association of the one or more antenna port associations. In particular embodiments, the selected antenna port association is based on an indication in the CSI configuration or in the request for the CSI report. Also refer to step 103 of FIGURE 8.

[0152] At step 1418, the wireless device computes CSI for the second set of CSI-RS portsaccording to the selected antenna port association and the channel measurements on the first set of CSI-RS ports. In particular embodiments, computing CSI for the second set of CSI-RS ports comprises interpolating measurements based on the channel measurements on the first set of CSI-RS ports. In particular embodiments, computing CSI for the second set of CSI-RS ports is based on output of a machine learning model whose input is based on the channel measurements on the first set of CSI-RS ports. Computing CSI for the second set of CSI-RS ports is described in more detail above with respect to particular embodiments and examples. Also refer to step 104 of FIGURE 8.

[0153] At step 1420, the wireless device reports the computed CSI to the network node in aCSI report. Also refer to step 105 of FIGURE 8.P110844WO01 PCT APPLICATION 32 of 44

[0154] In particular embodiments, the wireless device equates precoded physical downlinkshared channel, PDSCH, signals to corresponding symbols transmitted on the second set of CSI-RS ports.

[0155] At step 1422, the wireless device determines an accuracy of the computed CSI for thesecond set of CSI-RS ports based on a comparison of computed CSI for the second set of CSI- RS ports and actual channel measurements on the second set of CSI-RS ports.

[0156] For example, the network node may trigger a performance monitoring report from thewireless device where all ^^^^ = ^^^^^^ antenna (CSI-RS) ports are intermittently (e.g.,aperiodically) transmitted. The wireless device may then estimate the performance of itsconfigured ^^^^^^ < ^^^^ based AI / ML prediction. The UE may then report the performance ofcurrent configured port muting pattern to the network node.

[0157] 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.

[0158] FIGURE 15 is a flowchart illustrating an example method in a network node, accordingto certain embodiments. In particular embodiments, one or more steps of FIGURE 15 may be performed by network node 300 described with respect to FIGURE 13.

[0159] The method may begin at step 1510, where the network node (e.g., network node 300)receives a capability of a wireless device for computing CSI according to one or more of a number of CSI-RS ports in the first set, a number of CSI-RS ports in the second set, and a maximum number of interpolated CSI-RS ports. Receiving the configuration is described in more detail above with respect to step 1410 of FIGURE 14.

[0160] At step 1512, the network node transmits to a wireless device a CSI configuration. TheCSI configuration comprises one or more antenna port associations. Each of the one or more antenna port associations is between a first set of CSI-RS ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting. A number of CSI-RS ports in the first set is less than a number of CSI-RS ports in the second set. The CSI configuration is described in more detail above with respect to step 1412 of FIGURE 14.

[0161] At step 1414, the network node transmits a request to the wireless device for a CSIreport. The request is described in more detail above with respect to step 1414 of FIGURE 14.

[0162] At step 1416, the network node transmits CSI-RS on the first set of CSI-RS ports.Because the number of ports in the first set is less than the number of ports in the second set,P110844WO01 PCT APPLICATION 33 of 44 the network node is able to transmit fewer CSI-RS, which leaves more transmission resources available for other downlink activity.

[0163] At step 1418, the network node receives computed CSI for the second set of CSI-RSports from the wireless device in a CSI report. The CSI report is described in more detail above with respect to steps 1416-1420 of FIGURE 14.

[0164] Modifications, additions, or omissions may be made to method 1500 of FIGURE 15.Additionally, one or more steps in the method of FIGURE 15 may be performed in parallel or in any suitable order.

[0165] 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.

[0166] 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.

[0167] Although this disclosure has been described in terms of certain embodiments,alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the scope of this disclosure, as defined by the claims below.

[0168] Some example embodiments are described below.Group A Embodiments 1. A method performed by a wireless device, the method comprising:− receiving from a network node a channel state information (CSI) reporting configuration and CSI reference signal (RS) measurement resources and one orP110844WO01 PCT APPLICATION 34 of 44 more antenna port associations wherein each of the associations is between ^^^^^^CSI-RS ports used for channel measurements and ^^^^CSI-RS ports used for CSI computation and / or reporting; − receiving a request from the network node for CSI based on one of the antenna port associations; − performing channel measurements on the enabled / unmuted ^^^^^^antenna ports according to the indicated antenna port association; − computing CSI for ^^^^antenna ports, according to the indicated antenna port association; and − reporting computed CSI to the network node in a CSI report. 1. A method performed by a wireless device, the method comprising:− any of the wireless device steps, features, or functions described above, either alone or in combination with other steps, features, or functions described above. 2. The method of the previous embodiment, further comprising one or more additionalwireless device steps, features or functions described above. 3. The method of any of the previous two embodiments, further comprising:− providing user data; and − forwarding the user data to a host computer via the transmission to the base station. Group B Embodimentsby a base station, the method comprising:− transmitting to a wireless device a channel state information (CSI) reporting configuration and CSI reference signal (RS) measurement resources and one or more antenna port associations wherein each of the associations is between ^^^^^^CSI-RS ports used for channel measurements and ^^^^CSI-RS ports used for CSI computation and / or reporting; − transmitting a request to the wireless device for CSI based on one of the antenna port associations; − receiving computed CSI from the wireless device in a CSI report.P110844WO01 PCT APPLICATION 35 of 44 5. A method performed by a base station, the method comprising:− any of the steps, features, or functions described above with respect to base stations, either alone or in combination with other steps, features, or functions described above. 6. The method of the previous embodiment, further comprising one or more additionalbase station steps, features or functions described above. 7. The method of any of the previous embodiments, further comprising:− obtaining user data; and − forwarding the user data to a host computer or a wireless device. Group C Embodiments 8. A mobile terminal comprising:− circuitry configured to perform any of the steps of any of the Group A embodiments; and − power supply circuitry configured to supply power to the wireless device. 9. A base station comprising:− processing circuitry configured to perform any of the steps of any of the Group B embodiments; − power supply circuitry configured to supply power to the wireless device. 10. A user equipment (UE) comprising:− an antenna configured to send and receive wireless signals; − radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; − the processing circuitry being configured to perform any of the steps of any of the Group A embodiments; − an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; − an output interface connected to the processing circuitry and configured toP110844WO01 PCT APPLICATION 36 of 44 output information from the UE that has been processed by the processing circuitry; and − a battery connected to the processing circuitry and configured to supply power to the UE.

Claims

P110844WO01 PCT APPLICATION 37 of 44 CLAIMS:

1. A method performed by a wireless device, the method comprising: receiving (1412) from a network node a channel state information, CSI, configuration, the CSI configuration comprising one or more antenna port associations, wherein each of the one or more antenna port associations is between a first set of CSI reference signal, CSI-RS, ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting, wherein a number of CSI-RS ports in the first set is less than a number of CSI-RS ports in the second set; receiving (1414) a request from the network node for a CSI report; performing (1416) channel measurements on the first set of CSI-RS ports according to a selected antenna port association of the one or more antenna port associations; computing (1418) CSI for the second set of CSI-RS ports according to the selected antenna port association and the channel measurements on the first set of CSI-RS ports; and reporting (1420) the computed CSI to the network node in a CSI report.

2. The method of claim 1, wherein the computed CSI comprises a channel quality indicator, CQI, where the CQI is computed by the wireless device assuming precoded physical downlink shared channel, PDSCH, signals are equivalent to corresponding symbols transmitted on the second set of CSI-RS ports.

3. The method of any one of claims 1-2, wherein the antenna port association comprises a bitmap corresponding to each port of the second set of antenna ports, the bitmap indicating unmuted ports that correspond to the ports in the first set of CSI-RS ports.

4. The method of any one of claims 1-3, wherein receiving the CSI configuration comprises receiving a radio resource control, RRC, configuration message.

5. The method of any one of claims 1-4, wherein the selected antenna port association is based on an indication in the CSI configuration.

6. The method of any one of claims 1-5, wherein the one or more antenna portP110844WO01 PCT APPLICATION 38 of 44 associations are part of a CSI resource configuration.

7. The method of any one of claims 1-5, wherein the one or more antenna port associations are part of a CSI reporting configuration.

8. The method of any one of claims 1-7, wherein the request for a CSI report comprises an uplink related downlink control information.

9. The method of any one of claims 1-8, wherein the number of CSI-RS ports in the second set is equal to a full set of antenna ports.

10. The method of any one of claims 1-8, wherein the number of CSI-RS ports in the second set is less than a full set of antenna ports.

11. The method of claim 10, wherein each of the one or more antenna port associations comprises a second association between each of the second set of CSI-RS ports used for CSI reporting and the full set of antenna ports.

12. The method of any one of claims 1-11, wherein computing CSI for the second set of CSI-RS ports comprises interpolating measurements based on the channel measurements on the first set of CSI-RS ports.

13. The method of any one of claims 1-11, wherein computing CSI for the second set of CSI-RS ports is based on output of a machine learning model whose input is based on the channel measurements on the first set of CSI-RS ports.

14. The method of any one of claims 1-13, further comprising reporting (1410) a capability of the wireless device for computing CSI according to one or more of a number of CSI-RS ports in the first set, a number of CSI-RS ports in the second set, and a maximum number of interpolated CSI-RS ports.

15. The method of claim 14, wherein the capability of the wireless device forP110844WO01 PCT APPLICATION 39 of 44 computing CSI comprises a capability of the wireless device for computing CSI according to a first number of ports in a first dimension and a second number of ports in a second dimension.

16. The method of any one of claims 1-15, further comprising determining (1422) an accuracy of the computed CSI for the second set of CSI-RS ports based on a comparison of computed CSI for the second set of CSI-RS ports and actual channel measurements on the second set of CSI-RS ports.

17. A wireless device (200) comprising processing circuitry (202), the processing circuitry operable to: receive from a network node (300) a channel state information, CSI, configuration, the CSI configuration comprising one or more antenna port associations, wherein each of the one or more antenna port associations is between a first set of CSI reference signal, CSI-RS, ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting, wherein a number of CSI-RS ports in the first set is less than a number of CSI-RS ports in the second set; receive a request from the network node for a CSI report; perform channel measurements on the first set of CSI-RS ports according to a selected antenna port association of the one or more antenna port associations; compute CSI for the second set of CSI-RS ports according to the selected antenna port association and the channel measurements on the first set of CSI-RS ports; and report the computed CSI to the network node in a CSI report.

18. The wireless device of claim 17, wherein the computed CSI comprises a channel quality indicator, CQI, where the CQI is computed by the wireless device assuming precoded physical downlink shared channel, PDSCH, signals are equivalent to corresponding symbols transmitted on the second set of CSI-RS ports.

19. The wireless device of any one of claims 17-18, wherein the antenna port association comprises a bitmap corresponding to each port of the second set of antenna ports, the bitmap indicating unmuted ports that correspond to the ports in the first set of CSI-RS ports.P110844WO01 PCT APPLICATION 40 of 44 20. The wireless device of any one of claims 17-19, wherein the number of CSI-RS ports in the second set is equal to a full set of antenna ports.

21. The wireless device of any one of claims 17-19, wherein the number of CSI-RS ports in the second set is less than a full set of antenna ports.

22. The wireless device of claim 21, wherein each of the one or more antenna port associations comprises a second association between each of the second set of CSI-RS ports used for CSI reporting and the full set of antenna ports.

23. The wireless device of any one of claims 17-22, wherein the processing circuitry is operable to compute CSI for the second set of CSI-RS ports by interpolating measurements based on the channel measurements on the first set of CSI-RS ports.

24. The wireless device of any one of claims 17-22, wherein the processing circuitry is operable to compute CSI for the second set of CSI-RS ports based on output of a machine learning model whose input is based on the channel measurements on the first set of CSI-RS ports.

25. The wireless device of any one of claims 17-24, the processing circuitry further operable to report a capability of the wireless device for computing CSI according to one or more of a number of CSI-RS ports in the first set, a number of CSI-RS ports in the second set, and a maximum number of interpolated CSI-RS ports.

26. The wireless device of claim 25, wherein the capability of the wireless device for computing CSI comprises a capability of the wireless device for computing CSI according to a first number of ports in a first dimension and a second number of ports in a second dimension.

27. The wireless device of any one of claims 17-26, the processing circuitry further operable to determine an accuracy of the computed CSI for the second set of CSI-RS ports based on a comparison of computed CSI for the second set of CSI-RS ports and actual channelP110844WO01 PCT APPLICATION 41 of 44 measurements on the second set of CSI-RS ports.

28. A method performed by a network node, the method comprising: transmitting (1512) to a wireless device a channel state information, CSI, configuration, the CSI configuration comprising one or more antenna port associations, wherein each of the one or more antenna port associations is between a first set of CSI reference signal, CSI-RS, ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting, wherein a number of CSI-RS ports in the first set is less than a number of CSI-RS ports in the second set; transmitting (1514) a request to the wireless device for a CSI report; transmitting (1516) CSI-RS on the first set of CSI-RS ports; and receiving (1518) computed CSI for the second set of CSI-RS ports from the wireless device in a CSI report.

29. The method of claim 28, wherein the computed CSI comprises a channel quality indicator, CQI, where the CQI is computed by the wireless device assuming precoded physical downlink shared channel, PDSCH, signals are equivalent to corresponding symbols transmitted on the second set of CSI-RS ports.

30. The method of any one of claims 28-29, wherein the number of CSI-RS ports in the second set is equal to a full set of antenna ports.

31. The method of any one of claims 28-29, wherein the number of CSI-RS ports in the second set is less than a full set of antenna ports.

32. The method of claim 31, wherein each of the one or more antenna port associations comprises a second association between each of the second set of CSI-RS ports used for CSI reporting and the full set of antenna ports.

33. The method of any one of claims 28-32, further comprising receiving (1510) a capability of the wireless device for computing CSI according to one or more of a number of CSI-RS ports in the first set, a number of CSI-RS ports in the second set, and a maximumP110844WO01 PCT APPLICATION 42 of 44 number of interpolated CSI-RS ports.

34. The method of claim 33, wherein the capability of the wireless device for computing CSI comprises a capability of the wireless device for computing CSI according to a first number of ports in a first dimension and a second number of ports in a second dimension.

35. A network node (300) comprising processing circuitry (302), the processing circuitry operable to: transmit to a wireless device a channel state information, CSI, configuration, the CSI configuration comprising one or more antenna port associations, wherein each of the one or more antenna port associations is between a first set of CSI reference signal, CSI-RS, ports used for channel measurements and a second set of CSI-RS ports used for CSI reporting, wherein a number of CSI-RS ports in the first set is less than a number of CSI-RS ports in the second set; transmit a request to the wireless device for a CSI report; transmit CSI-RS on the first set of CSI-RS ports; and receive computed CSI for the second set of CSI-RS ports from the wireless device in a CSI report.

36. The network node of claim 35, wherein the computed CSI comprises a channel quality indicator, CQI, where the CQI is computed by the wireless device assuming precoded physical downlink shared channel, PDSCH, signals are equivalent to corresponding symbols transmitted on the second set of CSI-RS ports.

37. The network node of any one of claims 35-36, wherein the number of CSI-RS ports in the second set is equal to a full set of antenna ports.

38. The network node of any one of claims 35-36, wherein the number of CSI-RS ports in the second set is less than a full set of antenna ports.

39. The network node of claim 51, wherein each of the one or more antenna port associations comprises a second association between each of the second set of CSI-RS portsP110844WO01 PCT APPLICATION 43 of 44 used for CSI reporting and the full set of antenna ports.

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