Multi-layer (ML) user equipment (UE) multiple-input multiple-output (MIMO)

Abstract

A network node comprises means for receiving information originating from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE; means for performing UE-assisted allocation of one or more spatial transmit filters to the data stream according to the received information using at least one downlink transmission path spatially independent upon UE reception to achieve at least rank 4 for UE Multiple Input Multiple Output (MIMO).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to GB patent application No. 2302220.5 filed on February 16, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Examples of the present disclosure relate to ML UE-MIMO. Background Art

[0004] To implement multi-layer UE-MIMO, the required rank of MIMO is configured. Currently, this requires a thorough search for suitable downlink transmission paths that are spatially independent at reception. This consumes significant resources at both the network and the UE. Summary of the Invention

[0005] Examples provide UE-assisted assignment of one or more spatial transmit filters to data streams to achieve at least rank 4 of UE MIMO using at least one downlink transmission path that is spatially independent at UE reception.

[0006] According to various but not necessarily all examples, there is provided a network node comprising:

[0007] means for receiving information originating from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE;

[0008] Means for performing UE-assisted assignment of one or more spatial transmit filters to data streams based on the received information using at least one downlink transmission path that is spatially independent at the UE for reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

[0009] According to some, but not necessarily all, examples, UE-assisted assignment of one or more spatial transmit filters to data streams provides for multiple transmission paths that are spatially independent upon reception at the UE.

[0010] According to some but not necessarily all examples, the received information is an update to the network regarding the availability and / or unavailability of using the rank of the indicated beam.

[0011] According to some but not necessarily all examples, the indicated beam can be an existing beam, a currently active beam, or a currently inactive beam.

[0012] According to some, but not necessarily all, examples, the received information includes an indication of an achievable rank using at least one spatially independent downlink transmission path that is spatially independent when received by the UE.

[0013] According to some but not necessarily all examples,

[0014] Received information identifying at least one spatially independent downlink transmission path that is spatially independent when received by a UE

[0015] identifying at least: candidate downlink transmission paths, the candidate downlink transmission paths being candidates for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent when received by the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path;

[0016] and

[0017] A rank of multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at the UE for reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel is identified.

[0018] According to some, but not necessarily all, examples, the received information associates an achievable rank with a spatial transmit filter.

[0019] According to some but not necessarily all examples, the received information is used for UE directional downlink beam discovery for UE MIMO and reduces the search space for possible spatial filters for UE MIMO.

[0020] According to some but not necessarily all examples, UE directional downlink beam discovery for UE MIMO includes:

[0021] transmitting an N*M port reference signal (or an N times M port reference signal) on an indicated beam of one or more allocated spatial transmit filters; and

[0022] A rank report for the transmitted CSI-RS is received from the UE.

[0023] According to some but not necessarily all examples, UE-assisted assignment of one or more spatial transmit filters to data streams to achieve at least rank 4 for UE multiple-input multiple-output (MIMO) maximizes receive throughput at the UE.

[0024] According to some but not necessarily all examples, the received information indicates:

[0025] Availability of four receive ports for CSI-RS; and / or simultaneous availability of two receive ports for two CSI-RS.

[0026] According to some but not necessarily all examples, the received information indicates:

[0027] A candidate narrow beam for achieving rank N*M; or

[0028] Multiple candidate narrow beams for achieving rank N*M; or

[0029] The rank N*M cannot be achieved using the candidate narrow beam within the identified wide beam (SSB), and the candidate narrow beam within the identified wide beam for achieving the rank M is indicated.

[0030] According to some, but not necessarily all, examples, the network node is configured to use the candidate narrow beam for at least rank N*M transmission or for rank M transmission.

[0031] According to some but not necessarily all examples, the received information indicates:

[0032] Candidate narrow beams for achieving rank 4;

[0033] Candidate narrow beam pairs for achieving rank 4;

[0034] Rank 4 is not achievable using the candidate narrow beam within the identified wide beam, and candidate narrow beams within the identified wide beam for achieving rank 2 are indicated.

[0035] According to some, but not necessarily all, examples, the network node is configured to use the candidate narrow beam for rank-4 or rank-2 transmission.

[0036] According to some but not necessarily all examples, the received information indicates:

[0037] One TCI / CSI for 4 layers;

[0038] One TCI / CSI for 2 layers.

[0039] According to some but not necessarily all examples, the received information indicates:

[0040] A single CSI for achieving rank 4; or

[0041] a candidate CSI pair for achieving rank 4 associated with the same SSB; or

[0042] Candidate CSI associated with an SSB for achieving rank 2, where CSI in multiple SSBs is needed to achieve rank 4.

[0043] According to some, but not necessarily all, examples, the network node is configured to use the candidate CSI for rank-4 or rank-2 transmission.

[0044] According to some but not necessarily all examples, the received information indicates:

[0045] i) The first SSB and the first CSI are QCL-Type D,

[0046] ii) the first SSB and the first CSI are QCL-Type D, and the first SSB and the second CSI are QCL-Type D,

[0047] iii) the first SSB and the first CSI are QCL-TypeD, and the first SSB and other CSI are not QCL-TypeD,

[0048] or

[0049] The first SSB and the first CSI are QCL-TypeD, and the second SSB and the third CSI are QCL-TypeD.

[0050] According to various, but not necessarily all, examples, there is provided a computer program comprising instructions that, when executed by a processor, cause:

[0051] storing information received from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE;

[0052] UE-assisted assignment of one or more spatial transmit filters to data streams is performed based on the received information using at least one downlink transmission path that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

[0053] According to various but not necessarily all examples, there is provided a method comprising:

[0054] receiving information originating from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE;

[0055] UE-assisted assignment of one or more spatial transmit filters to data streams is performed based on the received information using at least one downlink transmission path that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

[0056] According to various but not necessarily all examples, there is provided a user equipment (UE), the UE comprising:

[0057] means for receiving a downlink reference signal associated with a spatially independent downlink transmission path when transmitted;

[0058] means for identifying at least a candidate downlink transmission path based on the receiving, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the UE reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path;

[0059] means for estimating a rank of multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at the UE for reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel;

[0060] Means for transmitting information identifying at least a candidate downlink transmission path and an estimated rank.

[0061] According to some but not necessarily all examples, the user equipment is configured to report to a network node a capability of identifying candidate downlink transmission paths and a rank for a UE multiple-input multiple-output (MIMO), the candidate downlink transmission paths being candidates for the UE multiple-input multiple-output (MIMO), the candidate downlink transmission paths including at least one candidate downlink transmission path.

[0062] According to some, but not necessarily all, examples, a user equipment is configured to receive a communication from a network node indicating a target rank.

[0063] According to some, but not necessarily all, examples, means for identifying at least a candidate downlink transmission path based on the receiving includes:

[0064] means for determining the presence of one or more downlink transmission paths associated with a wide downlink beam;

[0065] means for determining an association between one or more downlink transmission paths associated with a wide downlink beam and one or more narrow downlink beams;

[0066] Wherein the means for transmitting information identifying at least candidate downlink transmission paths and the estimated rank identifies one or more narrow downlink beams.

[0067] According to some, but not necessarily all, examples, the information is configured to identify whether a rank is available using a single candidate downlink transmission path or whether a rank is available using two downlink transmission paths.

[0068] According to some, but not necessarily all, examples, the information is configured to identify that a rank is unavailable using one or more downlink transmission paths in a set of downlink transmission paths associated with the wide downlink beam.

[0069] According to some but not necessarily all examples, based on information received from the network node, the QCL reports that the downlink beam associated with the one or more downlink transmission paths and the one or more narrow beams associated with the one or more downlink transmission paths are quasi co-located Type D.

[0070] According to various, but not necessarily all, examples, there is provided a computer program comprising instructions that, when executed by a processor, cause:

[0071] identifying, based on reception of downlink reference signals associated with the spatially independent downlink transmission paths at the time of transmission, at least a candidate downlink transmission path, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the time of reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path;

[0072] estimating a rank of a multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel;

[0073] Information identifying at least the candidate downlink transmission paths and the estimated rank is transmitted.

[0074] According to various but not necessarily all examples, there is provided a method comprising:

[0075] identifying, based on reception of downlink reference signals associated with the spatially independent downlink transmission paths at the time of transmission, at least a candidate downlink transmission path, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the time of reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path;

[0076] estimating a rank of a multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel;

[0077] Information identifying at least the candidate downlink transmission paths and the estimated rank is transmitted.

[0078] Examples are provided as claimed in the following claims according to various, but not necessarily exhaustive, examples.

[0079] Although the above examples and optional features of the present disclosure are described separately, it should be understood that they are provided in all possible combinations and arrangements and are included in the present disclosure. It should be understood that various examples of the present disclosure may include any or all features described with respect to other examples of the present disclosure, and vice versa. In addition, it should be understood that any one or more or all of these features in any combination may be implemented / included in / executable by a device, method and / or computer program instructions, as needed and appropriate. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Some examples will now be described with reference to the accompanying drawings, in which:

[0081] Figure 1 An example of the subject matter described herein is shown;

[0082] Figure 2 Another example of the subject matter described herein is shown;

[0083] Figure 3 Another example of the subject matter described herein is shown;

[0084] Figure 4A 、 Figure 4B 、 Figure 4C Other examples of the subject matter described herein are shown;

[0085] Figure 5 Another example of the subject matter described herein is shown;

[0086] Figure 6A 、 Figure 6B 、 Figure 6C Other examples of the subject matter described herein are shown;

[0087] Figure 7A 、 Figure 7B Another example of the subject matter described herein is shown;

[0088] Figure 8A 、 Figure 8B 、 Figure 8C Another example of the subject matter described herein is shown;

[0089] Figure 9A 、 Figure 9B 、 Figure 9C 、 Figure 9D Another example of the subject matter described herein is shown;

[0090] Figure 10 Another example of the subject matter described herein is shown;

[0091] Figure 11 Another example of the subject matter described herein is shown;

[0092] Figure 12 Another example of the subject matter described herein is shown;

[0093] Figure 13 Another example of the subject matter described herein is shown;

[0094] Figure 14 Another example of the subject matter described herein is shown;

[0095] Figure 15 Another example of the subject matter described herein is shown.

[0096] The figures are not necessarily to scale. For clarity and conciseness, certain features and views of the drawings may be shown schematically or exaggerated in scale. For example, the dimensions of certain elements in the figures may be exaggerated relative to other elements for ease of explanation. Similar reference numerals are used in the drawings to indicate similar features. For clarity, not all reference numerals are necessarily shown in all drawings.

[0097] In the following description, a class (or collection) may be referenced using a reference numeral without a subscript index (e.g., 10), a specific instance of a class (member of a collection) may be referenced using a reference numeral with a numeric subscript index (e.g., 10_1), and a non-specific instance of a class (member of a collection) may be referenced using a reference numeral with a variable subscript index (e.g., 10_i). DETAILED DESCRIPTION

[0098] Figure 1 The diagram illustrates an example of a network 100 comprising a plurality of network nodes, including a terminal node 110, an access node 120, and one or more core nodes 129. The terminal node 110 and the access node 120 are in communication with each other. The one or more core nodes 129 are in communication with the access node 120.

[0099] In this example, the network 100 is a wireless telecommunications network in which at least some of the terminal nodes 110 and the access nodes 120 communicate with each other using transmission / reception of radio waves.

[0100] In some examples, one or more core nodes 129 can communicate with each other. In some examples, one or more access nodes 120 can communicate with each other.

[0101] The network 100 may be a cellular network comprising a plurality of cells 122, each served by an access node 120. In this example, the interface between the terminal node 110 and the access nodes 120 defining the cells 122 is a wireless interface 124.

[0102] The access node 120 is a cellular radio transceiver. The terminal node 110 is a cellular radio transceiver.

[0103] In the illustrated example, the cellular network 100 is a Third Generation Partnership Project (3GPP) network in which the terminal nodes 110 are user equipments (UEs) and the access nodes 120 are base stations.

[0104] In the particular example shown, network 100 is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). E-UTRAN consists of E-UTRAN NodeBs (eNBs) 120, which provide E-UTRA user plane and control plane (RRC) protocol terminations to UE 110. eNBs 120 are interconnected via an X2 interface 126. The eNBs are also connected to a Mobility Management Entity (MME) 129 via an S1 interface 128.

[0105] In another example, network 100 is a next generation (or new radio NR) radio access network (NG-RAN). NG-RAN consists of gNodeBs (gNBs) 120, which provide user plane and control plane (RRC) protocol terminations to UE 110. gNBs 120 are interconnected via X2 / Xn interfaces 126. The gNBs are also connected to an access and mobility management function (AMF) via an N2 interface 128.

[0106] User equipment includes mobile devices. Where reference is made to user equipment, whenever possible, the reference includes and encompasses reference to mobile devices.

[0107] A downlink transmission beam is a downlink transmission that is steered to have a specific direction (angle of departure) and range. This can be achieved using spatial filters. Beams can have different characteristics. For example, a beam can be wide (large range) or narrow (small range).

[0108] In 3GPP, a beam is defined by a transmission configuration indicator (TCI) state, and the TCI state is indicated by the TCI. Therefore, a beam can be referred to as a TCI state (or TCI). One or more TCIs are mapped to a TCI state, and the TCI state is mapped to a beam.

[0109] 3GPP defines multiple reference signals (RS) for beam management.

[0110] New Radio (NR) synchronization signal (SS) blocks (SSBs) are downlink reference signals (DL-RSs) transmitted using wide beams. Channel state information reference signal (CSI-RS) resources are downlink reference signals (DL-RSs) transmitted using narrow beams.

[0111] In 3GPP, the gNB sweeps the SSB beam – it sends a sequence of SSB beams with different directions, and the UE detects the best beam among them.

[0112] In 3GPP, the gNB sweeps the CSI-RS beam—it sends a sequence of CSI-RS beams with different directions, and the UE detects the best beam among them.

[0113] The search for the best CSI-RS beam may be limited to searching for those CSI-RS beams that are spatially within the best SSB beam.

[0114] DL beam indication is based on the transmission configuration indication (TCI) state(s). The TCI state(s) are configured by radio resource control (RRC) and / or medium access control (MAC) control elements (CEs).

[0115] The UE may be configured by the gNB using a TCI state configuration. Each TCI state contains parameters for configuring a quasi co-location relationship between one or two downlink reference signals.

[0116] Two antenna ports are said to be quasi co-located if the properties of the channel over which symbols on one antenna port are transmitted can be inferred from the channel over which symbols on the other antenna port are transmitted.

[0117] The quasi co-location type corresponding to each DL RS is given by the high-level parameter qcl-Type in QCL-Info and can take one of the following values: QCL-TypeA: {Doppler shift, Doppler spread, average delay, delay spread}; QCL-TypeB: {Doppler shift, Doppler spread}; QCL-TypeC: {average delay, Doppler shift}; QCL-TypeD: {spatial Rx parameters}.

[0118] If two antenna ports are quasi-co-located in space (QCL Type D), this indicates that a beam direction that is favorable for one antenna port is also favorable for the other antenna port.

[0119] QCL-Type D may be used to provide a spatial relationship (eg, spatial overlap) between different reference signals.

[0120] Antenna port (AP) QCL can be used to indicate downlink Tx and Rx beams, where the Rx beam can be indicated by QCL with parameter QCL TypeD, which is configured in the TCI state referenced by TCI.

[0121] By design, multiple CSI-RSs are quasi-co-located (QCLed) with each synchronization signal block (SSB).

[0122] The Transmission Configuration Indicator (TCI) status is dynamically sent in a DCI message, which includes configurations such as the QCL relationship between DL RSs in one CSI-RS set and PDSCH DMRS ports.

[0123] Each TCI state contains parameters for configuring a quasi-co-location relationship between one or two downlink reference signals and the DM-RS port of the PDSCH, the DM-RS port of the PDCCH, or the CSI-RS port(s) of the CSI-RS resource.

[0124] The quasi co-location (QCL) relationship is configured by the higher layer (RRC Reconfig) parameter qcl-Type1 of the first DL RS and the higher layer (RRC Reconfig) parameter qcl-Type2 of the second DL RS. Up to two qcl-types can be configured for each TCI state.

[0125] The TCI state defines the QCL source and QCL-TypeD for the target reference signal and therefore indicates the transmission configuration, which includes the QCL relationship between the DL RSs in an RS set. The concept of UE panels is not in the specification, but it is understood that the DL and UL signals characterized by the TCI are received only by a subset of the panels used by the UE, and that the panels receiving the RSs identified by the TCI are the active panels used in the actual DL and UL transmissions.

[0126] Quasi-co-location of two antenna ports indicates that the channel conditions for symbols transmitted from these antenna ports are similar and can be extrapolated from one antenna port to the other. Based on the attribute set for channel conditions, 3GPP TS 38.214 defines the following QCL types: QCL-Type A, QCL-Type B, QCL-Type C, and QCL-Type D. QCL-Type D uses spatial Rx parameters to define channel conditions and is used to support beamforming.

[0127] The rank is the number of independent communication channels. If the channel matrix is ​​represented as a diagonal matrix, then the rank is the number of non-zero values ​​on the diagonal of the diagonal matrix.

[0128] For 2×2 MIMO, there are 2 input channels (DL@Tx)y and 2 output channels (DL@Rx)x, which are related by the channel matrix H:

[0129] y=H x

[0130] The channel matrix H can be decomposed into a combination of input and output correlation matrices and an interconnecting diagonal matrix D. The rank is the number of non-zero values ​​in D.

[0131] Figure 2 An example of a network node 120 is shown. For example, the network node 120 can be any suitable device in the network. It can be, for example, a transmission reception point (TRP). For example, it can be a base station, such as a gNB.

[0132] The network node 120 comprises means for receiving information 111 originating from a user equipment (UE) 110, the information identifying at least one spatially independent downlink transmission path 30 being spatially independent when received by the UE.

[0133] The network node 120 further comprises means for performing UE-assisted allocation 10 of one or more spatial transmit filters 12 to data streams 40 using at least one downlink transmission path 30 that is spatially independent upon UE reception in accordance with the received information 111 to achieve at least rank 4 for UE Multiple Input Multiple Output (MIMO).

[0134] In some examples, the means for receiving information 111 originating from a user equipment (UE) 110 (the information identifying at least one spatially independent downlink transmission path 30 that is spatially independent when received by the UE) is a data interface that receives the received information 111 from a base station or a transmission reception point. In some examples, the means for receiving information 111 originating from a user equipment (UE) 110 (the information identifying at least one spatially independent downlink transmission path 30 that is spatially independent when received by the UE) is a radio interface at the base station or the transmission reception point.

[0135] UE-assisted allocation 10 is configured to achieve at least rank 4 for UE multiple-input multiple-output (MIMO). UE-assisted allocation 10 assigns one or more spatial transmit filters 12 to multiple data streams 40 (multiple layers). Multiple data streams 40 are assigned to at least one downlink transmission path 30 determined by the assigned spatial filters 12. UE-assisted allocation 10 assigns the spatial filter(s) so that the downlink transmission paths 30 are spatially independent during reception.

[0136] The UE-assisted assignment 10 of one or more spatial transmit filters 12 to data streams 40 provides multiple transmission paths that are spatially independent upon reception at UE 110 .

[0137] Figure 3 An example of a user device 110 is illustrated.

[0138] The UE-assisted assignment 10 of one or more spatial transmit filters 12 to data streams 40 provides multiple downlink transmission paths 30 that are spatially independent upon reception at the UE 110 .

[0139] The received information 111 comprises an indication of a rank achievable using at least one spatially independent downlink transmission path 30 that is spatially independent when received by the UE.

[0140] In some but not necessarily all examples, the received information 111 identifying at least one spatially independent downlink transmission path 30 that is spatially independent when received by the UE identifies at least a candidate downlink transmission path 30 and a rank for UE multiple-input multiple-output (MIMO).

[0141] The candidate downlink transmission paths 30 are candidates for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths 30 that are spatially independent at the time of UE reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path. The rank is the rank for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths 30 that are spatially independent at the time of UE reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel.

[0142] In some, but not necessarily all, examples, reference Figure 4A 、 Figure 4B 、 Figure 4C , user equipment (UE) 110 includes:

[0143] means for receiving a downlink reference signal 20, 30 associated with a spatially independent downlink transmission path 30 when transmitted;

[0144] means for identifying, based on the receiving, at least a candidate downlink transmission path 30, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using a plurality of simultaneous downlink transmission paths 30 that are spatially independent at the UE reception, the plurality of simultaneous downlink transmission paths including at least one candidate downlink transmission path 30;

[0145] means for estimating a rank for a UE multiple-input multiple-output (MIMO) using a plurality of simultaneous downlink transmission paths 30 that are spatially independent at the UE for reception, the plurality of simultaneous downlink transmission paths comprising at least one candidate downlink transmission channel;

[0146] Means for sending information 111 identifying at least a candidate downlink transmission path 30 and an estimated rank.

[0147] In this example, the downlink reference signal associated with the spatially independent downlink transmission path 30 may be sent as a wide beam 22 (eg, SSB) when transmitted.

[0148] In this example, the downlink reference signal associated with the spatially independent downlink transmission path 30 may be sent as a narrow beam 20 (eg, CSI-RS) when transmitted.

[0149] The received information 111 associates the achievable rank with the spatial transmit filter 12. This association may be explicit or implicit; direct or indirect.

[0150] In some examples, the received information 111 associates an achievable rank with the spatial transmit filter 12 because the received information indicates:

[0151] DL beam (which is formed by the spatial transmit filter 12);

[0152] TCI status (which defines the downlink beam);

[0153] TCI (which maps to TCI status); or

[0154] CSI-RS (which is formed by the spatial transmit filter 12).

[0155] The association or indication may be direct or indirect, eg via another mapping or correlation, eg via a QCL.

[0156] For example, the identification of a single narrow beam (or TCI / CSI) can implicitly indicate that rank 4 is achievable using one spatial filter (one downlink transmission path 30). For example, the identification of a single wide beam (or SSB) can implicitly indicate that rank 4 is achievable using two spatial filters (two downlink transmission paths 30 within the wide beam). For example, the identification of two beams can implicitly indicate that rank 4 is achievable using two spatial filters (two downlink transmission paths 30 within the identified beam, which can be wide or narrow). A beam is defined by an associated downlink reference signal (DL-RS) or TCI state. Examples of DL-RS include SSB and CSI-RS.

[0157] The received information 111 is used by the network node 120 for UE directional downlink beam discovery for UE MIMO. The received information 111 reduces the search space of possible spatial filters for UE-MIMO. The search space of possible spatial filters can be limited to spatial filters associated with reception, for example, on certain channels and bandwidth portions. The search space of possible spatial filters can be constrained to spatial filters associated with transmission, for example, on certain channels and bandwidth portions.

[0158] In some examples, the received information 111 reduces the search space of possible transmission configuration indicators (TCIs) for UE-MIMO.

[0159] In some examples, the received information 111 is an update to the network regarding the availability and / or unavailability of using a rank of an indicated beam. The beam may be indicated in any suitable manner. For example, one or more beams may be indicated as a set (SSB indicates a CSI set) or specifically (CSI / TCI). For example, the indicated one or more beams may be wide beams or narrow beams. The indicated beam may be an existing beam, a currently active beam, or a currently inactive beam.

[0160] The TCI defines a TCI state, which defines a spatial transmit filter 12, which defines a downlink beam.

[0161] UE directional downlink beam discovery for UE MIMO includes:

[0162] A 4-port CSI-RS (or a 2-port CSI-RS) is transmitted on the indicated beam of the one or more assigned spatial transmit filters 12, and a rank report for the transmitted CSI-RS is received from the UE 110. This confirms that the UE-assisted assignment 10 of the one or more spatial transmit filters 12 to the data stream 40 relies on the received information 111 to achieve rank 4.

[0163] In at least some examples, UE-assisted assignment 10 of one or more spatial transmit filters 12 to data streams 40 to achieve at least rank 4 for UE multiple-input multiple-output (MIMO) maximizes receive throughput at UE 110 .

[0164] Figure 4A 、 Figure 4B and Figure 4C The figure shows different situations of downlink transmission, which can be obtained as follows Figure 3 The existence of multiple downlink transmission paths 30 that are spatially independent at the UE reception is shown.

[0165] Figure 4A The first scenario (Case 1) is illustrated, in which a single spatial transmit filter 12 defines a narrow downlink beam 20, which is used to provide a single downlink transmission path 30 during transmission. Radio channel effects (such as multipath reflections) result in the presence of two spatially independent downlink transmission paths 30 when received by the UE. The two spatially independent downlink transmission paths 30 are quasi-co-located (QCL) Type D with each other when received by the UE.

[0166] Figure 4BThe second scenario (Case 2) is illustrated, in which a first spatial transmit filter 12_1 defines a first narrow downlink beam 20_1, which is used to provide a first downlink transmission path 30_1 during transmission, and a second spatial transmit filter 12_2 defines a second narrow downlink beam 20_2, which is used to provide a second downlink transmission path 30_2 during transmission. The two downlink transmission paths 30_1 and 30_2 are spatially independent when received by a UE, but they are not quasi-co-located (QCL) with each other. The first downlink transmission path 30_1 is a QCL Type D with a wide downlink beam 22, and the second downlink transmission path 30_2 is a QCL Type D with the same wide downlink beam 22.

[0167] Figure 4C The third scenario (Case 3) is illustrated, in which the first spatial transmit filter 12_1 defines a first narrow downlink beam 20_1, which is used to provide a first downlink transmission path 30_1 during transmission, and the second spatial transmit filter 12_2 defines a second narrow downlink beam 20_2, which is used to provide a second downlink transmission path 30_2 during transmission. The two downlink transmission paths 30_1 and 30_2 are spatially independent when received by the UE, but they are not quasi-co-located (QCL) with each other. The first downlink transmission path 30_1 is of QCL Type D with a first wide downlink beam 22_1, and the second downlink transmission path 30_2 is of QCL Type D with a second, different wide downlink beam 22_2.

[0168] In case 1( Figure 4A ), 4 receive ports may be used for narrow beams (eg, CSI-RS). In this case, the received information 111 may indicate the availability of 4 receive ports for CSI-RS.

[0169] In cases 2 and 3 ( Figure 4B 、 Figure 4C ), two receive ports may be used simultaneously for each of two narrow beams (e.g., CSI-RS). In this case, the received information 111 may indicate the simultaneous availability of two receive ports for two CSI-RS.

[0170] The received information 111 can have a variety of forms and still achieve the desired effect of at least rank 4 for UE multiple-input multiple-output (MIMO) using at least one downlink transmission path 30 that is spatially independent when received by the UE to provide UE assistance for UE assisted allocation 10 of one or more spatial transmit filters 12 to data streams 40 to achieve the desired effect of at least rank 4 for UE multiple-input multiple-output (MIMO).

[0171] In some, but not necessarily all, examples, the received information 111 indicates:

[0172] (i) Candidate narrow beams (e.g., CSI) for achieving rank 4 (Case 1);

[0173] (ii) Candidate narrow beam pairs (e.g., 2 CSIs) for achieving rank 4 (Case 2);

[0174] (iii) Rank 4 cannot be achieved using a candidate narrow beam within the identified wide beam (eg, SSB), and a candidate narrow beam within the identified wide beam is indicated for achieving rank 2 (Case 3).

[0175] In options (i) and (ii), rank 4 is already achieved (or expected to be achieved). Therefore, the requirement to perform an exhaustive search to assign spatial transmit filter(s) 12 to data streams 40 to achieve rank 4 for UE multiple-input multiple-output (MIMO) is eliminated.

[0176] In option (iii), rank 4 has not yet been achieved (or is not expected to be achieved). However, the search space that needs to be searched to assign spatial transmit filter(s) 12 to data streams 40 to achieve rank 4 for UE multiple-input multiple-output (MIMO) is reduced.

[0177] In some, but not necessarily all, examples, the received information 111 indicates:

[0178] A single CSIQCL-TypeD for implementing rank 4 (case 1), or

[0179] Candidate CSI pairs for achieving rank 4 associated with the same SSB (Case 2), or

[0180] Candidate CSI associated with an SSB for achieving rank 2, where CSI in multiple SSBs is needed to achieve rank 4 (case 3).

[0181] In some, but not necessarily all, examples, the received information 111 indicates:

[0182] i) The first SSB and the first CSI are QCL-Type D (Case 1), or

[0183] ii) the first SSB and the first CSI are QCL-Type D, and the first SSB and the second CSI are QCL-Type D (Case 2), or

[0184] iii) the first SSB and the first CSI are QCL-Type D, and the second SSB and the third CSI are QCL-Type D (Case 3), or

[0185] The first SSB and the first CSI are QCL-TypeD, and the first SSB and the other CSI are not QCL-TypeD (a variant of case 3)

[0186] Figure 5 An example of the network node 120 controlling UE-MIMO performance is illustrated.

[0187] As previously mentioned, but not illustrated in this figure, the network node 120 receives information 111 originating from a user equipment (UE) 110 identifying at least one spatially independent downlink transmission path 30 that is spatially independent when received by the UE.

[0188] The network node 120 performs UE-assisted allocation 10 of one or more spatial transmit filters 12 to data streams 40 based on the received information 111 using at least one downlink transmission path 30 that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

[0189] Figure 5 The use of one or more spatial transmit filters 12 assigned to data streams 40 as described above to achieve at least rank 4 for UE multiple-input multiple-output (MIMO) is illustrated.

[0190] In the previous example, there was an unstated assumption that two spatially independent downlink transmission paths 30 at reception were sufficient to achieve rank 4. This means that each spatially independent downlink transmission path 30 at reception enables rank 2. This is most likely achieved by transmitting orthogonal dual-polarized signals in the downlink transmission paths 30.

[0191] However, the present invention has broader application. Let each downlink transmission path 30 have rank M available, and let N spatially independent downlink transmission paths be available. The available rank is N*M. In the previous example, N=2 and M=2, but this is not always the case. In some examples, N>1 and M≥1.

[0192] In some examples, UE directional downlink beam discovery for UE MIMO includes:

[0193] An N*M-port reference signal (or an N-times-M-port reference signal) is transmitted on the indicated beams of one or more allocated spatial transmit filters 12 , and a rank report of the transmitted CSI-RS is received from UE 110 .

[0194] In some, but not necessarily all, examples, the reference signal is a CSI-RS.

[0195] In some but not necessarily all examples, UE-assisted assignment 10 of one or more spatial transmit filters 12 to data streams 40 to achieve at least rank N*M for UE multiple-input multiple-output (MIMO) maximizes receive throughput at UE 110 .

[0196] In some, but not necessarily all, examples, the received information 111 indicates:

[0197] Availability of N*M receive ports for CSI-RS; and / or simultaneous availability of M receive ports for N CSI-RS.

[0198] In some, but not necessarily all, examples, the received information 111 indicates:

[0199] One candidate narrow beam (e.g., CSI) for achieving rank N*M; or

[0200] Multiple candidate narrow beams (e.g., N CSIs) for achieving rank N*M; or

[0201] Rank N*M cannot be achieved using the candidate narrow beam within the identified wide beam (SSB),

[0202] And the candidate narrow beams for achieving rank M within the identified wide beam are indicated.

[0203] In some, but not necessarily all, examples, the received information 111 indicates:

[0204] One TCI / CSI for N*M layers; or

[0205] One TCI / CSI for M layers.

[0206] In some, but not necessarily all, examples, the received information 111 indicates:

[0207] Used to implement a single CSI of rank N*M, QCL TypeD, or

[0208] N candidate CSIs associated with the same SSB for achieving rank N*M, or candidate CSIs associated with an SSB for achieving rank M, where CSIs in multiple SSBs are needed to achieve rank N*M.

[0209] In some, but not necessarily all, examples, the received information 111 indicates:

[0210] i) N CSIs are QCL-Type D, or

[0211] ii) SSB and each of the N CSIs is QCL-Type D, or

[0212] iii) The first SSB and one or more CSIs are QCL-TypeD, and the first SSB and other CSIs are not QCL-TypeD

[0213] or

[0214] The first SSB and one or more CSIs are QCL-TypeD, and the second SSB and one or more CSIs are QCL-TypeD.

[0215] As can be appreciated from the above description, in at least some examples, user equipment (UE) 110 includes:

[0216] means for receiving a downlink reference signal (RS) (e.g., SSB or CSI-RS) associated with a spatially independent downlink transmission path when transmitted;

[0217] means for identifying, based on the receiving, at least a candidate downlink transmission path 30, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using a plurality of simultaneous downlink transmission paths 30 that are spatially independent at the UE reception, the plurality of simultaneous downlink transmission paths including at least one candidate downlink transmission path 30;

[0218] means for estimating a rank for a UE multiple-input multiple-output (MIMO) using a plurality of simultaneous downlink transmission paths 30 that are spatially independent at the UE for reception, the plurality of simultaneous downlink transmission paths comprising at least one candidate downlink transmission channel;

[0219] Means for transmitting information identifying at least a candidate downlink transmission path and an estimated rank.

[0220] The means for receiving a downlink reference signal (RS) (eg, SSB or CSI-RS) associated with a spatially independent downlink transmission path when transmitted may be existing circuitry that may be used for the beam management process.

[0221] Figure 4 Figure 4B 、 Figure 4C The creation of one or more spatially independent downlink transmission paths at the time of transmission is illustrated in . This includes candidate downlink transmission path(s) 30 .

[0222] Figures 4A-4C The reception of at least one candidate downlink transmission path is illustrated in . These figures illustrate multiple simultaneous downlink transmission paths 30 that are spatially independent when received by a UE.

[0223] UE Multiple Input Multiple Output (MIMO) can use multiple simultaneous downlink transmission paths 30 ( Figure 3 ), including at least one candidate downlink transmission channel ( Figure 4A 、 Figure 4B 、 Figure 4C ).

[0224] In some, but not necessarily all, examples, UE 110 is configured to report to network node 120 a capability identifying candidate downlink transmission paths and a rank for a multiple-input multiple-output (MIMO) of the UE, the candidate downlink transmission paths being candidates for the multiple-input multiple-output (MIMO) of the UE, the candidate downlink transmission paths including at least one candidate downlink transmission path.

[0225] In some, but not necessarily all, examples, UE 110 is configured to receive a communication from a network node indicating a target rank.

[0226] In some, but not necessarily all, examples, UE 110 is configured to identify at least one candidate downlink transmission path based on the reception using a process comprising:

[0227] determining the presence of one or more downlink transmission paths associated with a wide downlink beam;

[0228] determining an association between one or more downlink transmission paths associated with the wide downlink beam and one or more narrow downlink beams;

[0229] Wherein the means for transmitting information identifying at least candidate downlink transmission paths and the estimated rank identifies one or more narrow downlink beams.

[0230] For example, detection of a wide beam cluster may be used to determine the presence of one or more downlink transmission paths associated with the wide downlink beam.

[0231] For example, detection of a cluster of narrow beams may be used to determine the presence of one or more downlink transmission paths associated with the narrow downlink beams.

[0232] The time correlation (synchronicity) between the wide beam cluster and the narrow beam cluster enables the downlink transmission path associated with the wide beam cluster to be correlated with the downlink transmission path associated with the synchronized narrow beam cluster.

[0233] Thus, an association between one or more downlink transmission paths associated with a wide downlink beam and one or more narrow downlink beams may be determined based on cluster detection and analysis.

[0234] In some, but not necessarily all, examples, at least the information identifying the candidate downlink transmission paths and the estimated ranks is configured to: identify whether the ranks are available using a single candidate downlink transmission path or whether the ranks are available using two downlink transmission paths. The rank order may be predetermined prior to transmission of this information.

[0235] In some but not necessarily all examples, at least the information identifying the candidate downlink transmission paths and the estimated rank is configured to identify that the rank is unavailable using one or more downlink transmission paths in the set of downlink transmission paths associated with the wide downlink beam.

[0236] In some but not necessarily all examples, the information identifying at least the candidate downlink transmission path and the estimated rank is configured to indicate: one candidate narrow beam for achieving rank N*M; or multiple candidate narrow beams for achieving rank N*M. In some but not necessarily all examples, the information is configured to indicate that rank N*M cannot be achieved using a candidate narrow beam within the identified wide beam (SSB), and to indicate a candidate narrow beam within the identified wide beam for achieving rank N.

[0237] In some, but not necessarily all, examples, candidate downlink paths (narrow beams) for transmission are indicated using TCI or CSI.

[0238] In some, but not necessarily all, examples, based on information received from a network node (e.g., a QCL report), a downlink beam associated with one or more downlink transmission paths and one or more narrow beams associated with the one or more downlink transmission paths are quasi-co-located Type D. The information may be configured to use a QCL Type D indication to identify that a rank is available.

[0239] In some, but not necessarily all, examples, the information identifying at least the candidate downlink transmission paths and the estimated rank indicates:

[0240] i) The first SSB and the first CSI are QCL-Type D, or

[0241] ii) The first SSB and the first CSI are QCL-Type D, and the first SSB and the second

[0242] CSI is QCL-TypeD, or

[0243] iii) The first SSB and the first CSI are QCL-TypeD, and the first SSB and other CSI are not QCL-TypeD

[0244] or

[0245] The first SSB and the first CSI are QCL-TypeD, and the second SSB and the third CSI are QCL-TypeD.

[0246] In the following example, UE 110 indicates to network 120 candidate gNB beams (associated DL-RS / TCI states) that can be paired to achieve the maximum likelihood of rank 4. The network may then schedule 4-port CSI-RS (or 2×2-port CSI-RS) on the indicated beams, and the UE will report the rank for the pair.

[0247] The network configures the UE with a list of reference signals for multi-source detection. The UE measures the PDP of the reference signal to be measured (SSB and CSI-RS belonging to the SSB beam, i.e., CSI-RS of QCL-TypeD with the same SSB). The UE identifies and compares the PDP cluster of each RS. For example, the UE identifies the cluster of each RS with the timestamp of each receive tap of the PDP (even if the receive power of each tap may be different). Based on the PDP of the reference signal pair (SSB and CSI-RS), the UE identifies that it is in three different scenarios ( Figure 5 In which of the following scenarios 1, 2, and 3) does the system run and reports to the network accordingly:

[0248] Case 1: In this case, the two clusters detected in the PDP of SSB#x are also found in the PDP of CSI#y beam. The UE then indicates to the network that rank 4 may be on CSI#y, and the network schedules a 4-port CSI-RS (i.e., DL Tx spatial filter) using this CSI#y beam.

[0249] Case 2: In this case, only one of the clusters of the PDP of SSB#x is found in the PDP of CSI#y. This indicates that the second cluster belongs to another CSI beam within the same SSB beam (i.e., another CSI that is QCL-TypeD with SSB#x), and

[0250] This pair of CSI-RS is reported by the UE to the network because it is likely to produce rank 4. Then,

[0251] The network schedules 2-port CSI-RS on each reported CSI / TCI of the pair simultaneously. Case 3: In this case, the SSB beam contains only a single cluster, so any combination of CSI-RS belonging to this SSB will not produce rank 4. The UE indicates to the network that rank 4 can be found from CSI / TCI pairs belonging to different SSB beams (and associated SSB beam indices). The network then schedules CSI-RS from each SSB beam, and the UE can measure these beams and indicate CSI / TCI pairs that may produce rank 4, as shown in Case 2. The network then schedules 2-port CSI-RS on each reported CSI / TCI of the pair simultaneously. The network then schedules 2-port CSI-RS on each reported CSI / TCI of the pair simultaneously.

[0252] Based on cases 1, 2, and 3, the UE reports to the network the beam pair with the highest likelihood of a rank 4 pair (i.e., PDSCH can be scheduled for 4-layer DL MIMO). Otherwise, the pair is only a candidate for rank 2 (i.e., receiving PDCCH / 2-layer PDSCH repetitions). When the pair is only a candidate for rank 2, even if rank 4 cannot be performed using the pair, the pair can still be used for rank 2 transmission and repeated for connection reliability.

[0253] Based on the UE indication for each of cases 1, 2, and 3, the network schedules CSI 4 ports on the reported beam.

[0254] The UE measures and reports the rank, and the network uses this information to schedule the PDSCH.

[0255] The proposed idea will significantly speed up the discovery of the appropriate CSI beam pair. The discovery and reporting is performed by the UE, rather than the gNB blindly scheduling CSI 4 ports in the hope of finding the correct beam pair.

[0256] These three different situations are Figure 6A 、 Figure 6B 、 Figure 6C shown.

[0257] Figure 6A The figure shows Case 1. CSI#y and SSB#x are QCL-Type D. The same CSI-RS provides two spatially independent downlink transmission paths when the UE receives, and 4 ports (4 data streams) can be configured for MIMO rank 4 (4-layer MIMO).

[0258] Figure 6BCase 2 is illustrated. CSI#y and CSI#z are not QCL-TypeD. However, CSI#y and SSB#x are QCL-TypeD, and CSI#z and SSB#x are QCL-TypeD. Two CSI-RSs are required to provide two spatially independent downlink transmission paths when the UE receives. CSI#y is configured with 2 ports (2 data streams), and CSI#z is configured with 2 ports (2 data streams) to achieve MIMO rank 4 (4-layer MIMO).

[0259] Figure 6C The diagram shows Case 3. CSI#y and SSB#x are QCL-TypeD. CSI#m and SSB#w are QCL-TypeD. SSB#x and SSB#w are not QCL-TypeD. CSI#y and CSI#m are not QCL-TypeD. Two CSI-RSs (not QCL-TypeD with the same SSB) are required to provide two completely independent downlink transmission paths when the UE receives. CSI#y is configured with 2 ports (2 data streams) and CSI#m is configured with 2 ports (2 data streams) to achieve MIMO rank 4 (4-layer MIMO).

[0260] UE 110 identifies which case it is operating in and indicates this to the network to assist the gNB in ​​finding the CSI beam pair with the highest likelihood of producing rank-4 MIMO.

[0261] Figure 7A and Figure 7B Pictured Figure 6A Cluster detection and analysis for Case 1 shown.

[0262] like Figure 7A As shown, PDP is received from SSB#x at the UE. It has two different clusters, cluster 1 and cluster 2.

[0263] like Figure 7B As shown, PDP is received at the UE from CSI#y within SSB#x. It has two different clusters, cluster 1 and cluster 2.

[0264] Cluster 1 and cluster 2 in the PDP for SSB#x are time-correlated (synchronized) with cluster 1 and cluster 2 in the PDP for CSI#y.

[0265] The UE determines that the two clusters detected in SSB#x belong to CSI#y beam because the timestamps match (the power may be different). It can be inferred that 4-layer downlink MIMO is likely from the 4-port CSI in the current active TCI state.

[0266] The UE indicates to the gNB that the CSI beam used for 4-layer MIMO is likely to be QCL Type D.

[0267] In this example, CSI#y and SSB#x are QCL-Type D. The same CSI-RS is configured with 4 ports.

[0268] Figure 8A 、 Figure 8B 、 Figure 8C Pictured Figure 6B Cluster detection and analysis shown for Case 2. Two variants of Case 2 are described as Case 2A and Case 2B. Figure 8A and Figure 8B Related to Scenario 2A. Figure 8A 、 Figure 8B and Figure 8C Related to situation 2B.

[0269] refer to Figure 8A and Figure 8B Example describing situation 2A:

[0270] Figure 8A The diagram shows the PDP received from SSB#x at the UE. It has two different clusters, cluster 1 and cluster 2.

[0271] like Figure 8B As shown, a PDP is received at the UE from CSI#y within SSB#x. It has one cluster, cluster 1. Cluster 1 in the PDP for SSB#x is time-correlated (synchronized) with cluster 1 in the PDP for CSI#y.

[0272] Cluster 2 in the PDP for SSB#x has no time correlation (synchronization) with any cluster in the PDP for CSI#y.

[0273] The UE determines that clusters 1 and 2 are part of the same SSB beam, but not the same CSI beam. Cluster 2 belongs to another (unidentified) CSI beam within the same SSB beam. 4-layer MIMO is likely from 2×2 port CSI beams belonging to the same SSB spatial filter.

[0274] The UE indicates to the gNB that the 4-layer CSI beams may belong to the same SSB.

[0275] This can be reported to the network. The UE indicates the CSI beams used for Layer 2 MIMO to the gNB.

[0276] refer to Figure 8A 、 Figure 8B and Figure 8C Example describing situation 2B:

[0277] Figure 8A The diagram shows the PDP received from SSB#x at the UE. It has two different clusters, cluster 1 and cluster 2.

[0278] like Figure 8B As shown, a PDP is received at the UE from CSI#y within SSB#x. It has a cluster 1. Cluster 1 in the PDP for SSB#x is time-correlated (synchronized) with cluster 1 in the PDP for CSI#y.

[0279] like Figure 8C As shown, a PDP is received at the UE from CSI#z within SSB#x. It has a cluster 2. Cluster 2 in the PDP for SSB#x is time-correlated (synchronized) with cluster 2 in the PDP for CSI#z.

[0280] Cluster 2 in the PDP for SSB#x has no time correlation (synchronization) with any cluster in the PDP for CSI#y. Cluster 1 in the PDP for SSB#x has no time correlation (synchronization) with any cluster in the PDP for CSI#z.

[0281] The UE determines that cluster 1 detected in SSB #x belongs to the CSI #y beam because the timestamps match (the power can be different). When the timestamps match, the UE determines that cluster 2 detected in SSB #x belongs to the CSI #z beam (even though the power levels can be different). Therefore, the UE can infer that 4-layer downlink MIMO is most likely achieved by scheduling a 2-port CSI #y and 2-port CSI #z pair.

[0282] The UE indicates the CSI beam used for 2×2 layer MIMO to the gNB.

[0283] In this example, CSI#y and CSI#z are not QCL-Type D. However, CSI#y and SSB#x are QCL-Type D, and CSI#z and SSB#x are QCL-Type D. CSI#y is configured with 2 ports. CSI#z is configured with 2 ports.

[0284] Figure 9A 、 Figure 9B 、 Figure 9C 、 Figure 9D Pictured Figure 6C Cluster detection and analysis shown for Case 3. Two variants of Case 3 are described as Case 3A and Case 3B. Figure 9A Related to Scenario 3A. Figure 9A 、 Figure 9B 、 Figure 9C and Figure 9D Related to situation 3B.

[0285] refer to Figure 9A Example describing situation 3A:

[0286] Figure 9AThe diagram shows the PDP received from SSB#x at the UE. It has less than two different clusters. It has one different cluster, cluster 1.

[0287] The UE determines that it does not need to compare with the PDP of the CSI within SSB#x because SSB#x includes less than two different clusters.

[0288] This can be reported to the network. The UE indicates to the gNB that SSB#x itself cannot support 4-layer MIMO.

[0289] The UE indicates to the gNB that the 4-layer CSI beams may belong to different SSBs.

[0290] The UE may indicate to the gNB that it can natively support 2-layer MIMO if SSB#x has a single cluster.

[0291] To find 4-layer downlink MIMO, the UE must find another cluster, e.g., from another SSB, and then select the best CSI beam within the second SSB.

[0292] refer to Figure 9A 、 Figure 9B 、 Figure 9C 、 Figure 9D Example describing situation 3B:

[0293] Figure 9A The diagram shows the PDP received at the UE from SSB#x. It has a different cluster, cluster 1.

[0294] like Figure 9B As shown, the PDP received at the UE from CSI#y within SSB#x has one cluster 1. Cluster 1 in the PDP for SSB#x is time-correlated (synchronized) with cluster 1 in the PDP for CSI#y.

[0295] like Figure 9C As shown, the PDP received from SSB#w at the UE has a different cluster, namely cluster 2.

[0296] like Figure 9D As shown, the PDP received at the UE from CSI#m within SSB#w has one cluster 2. Cluster 2 in the PDP for SSB#w is time-correlated (synchronized) with cluster 2 in the PDP for CSI#m.

[0297] Note that cluster 1 in the PDP for SSB#x has no time correlation (synchronous) with any cluster in the PDP for CSI#m. Note that cluster 2 in the PDP for SSB#w has no time correlation (asynchronous) with any cluster in the PDP for CSI#y.

[0298] The UE determines that 4 layers of MIMO can come from 2×2 port CSI beams belonging to different SSB spatial filters.

[0299] This can be reported to the network. The UE indicates two different CSI beams to the gNB, one for each layer of MIMO.

[0300] In this example, CSI#y and SSB#x are QCL-Type D. The gNB needs to scan the CSI-RS of SSB#w to find, for example, CSI#m.

[0301] In this example, CSI#m and SSB#w are QCL-TypeD.

[0302] CSI#y and CSI#m are not QCL-TypeD.

[0303] CSI#y is configured with 2 ports. CSI#m is configured with 2 ports.

[0304] Figure 10 Illustrated is the method performed by the UE to achieve rank 4 DL MIMO when estimating up to 2 clusters in SSB. Specially designed boxes are denoted by "*".

[0305] At block 301 , the UE is in RRC_Connected and scheduled for 1 or 2 layers in downlink in 1TCI ​​state.

[0306] At block 302, the UE measures SS bursts and stores the PDP of the SSB with the best RESPR, eg, within 3 dB.

[0307] At block 303 , the UE measures the active TCI state (ie, CSI-RS) and stores the PDP, eg, 4 CSI-RS of the same SSB.

[0308] At block 304*, the UE compares the PDP of the SSB with the PDP of each CSI-RS.

[0309] At block 305*, the UE determines whether there are two clusters in the SSB PDP. If so, the method moves to block 306, if not, the method moves to block 330 (case 3).

[0310] At block 306*, the UE determines whether all clusters in the SSB PDP are present in the PDP of the active CSI. If 'yes', the method moves to block 310 (case 1), and if 'no', the method moves to block 320 (case 2).

[0311] At block 310*, the UE indicates to the network that there is the highest possibility to find rank 4 by scheduling 4-port CSI on the current active TCI state (the UE may send CSI-RS index, TCI index, add flags, etc.).

[0312] At block 311 , the network schedules 4-port CSI on the active TCI.

[0313] At block 312, the UE measures and reports rank 4 in a CSI report.

[0314] At block 313, the network schedules layer 4 downlink MIMO.

[0315] At block 320*, the UE indicates to the network the CSI index for which there is the highest probability of finding rank 4 by scheduling 2-port CSI simultaneously on each CSI index (the UE may send CSI-RS index, TCI index, add flags, etc.).

[0316] At block 321 , the network schedules 2-port CSI on the two indicated CSI beams.

[0317] At block 322, the UE measures and reports rank 4 in a CSI report.

[0318] At block 323, the network schedules layer 4 downlink MIMO.

[0319] At box 330*, the UE indicates to the network the SSB index whose CSI-RS can be scheduled so as to find the highest likelihood beam pair with rank 4 by simultaneously scheduling 2-port CSI on each SSB index (the UE can send SSB index, TCI index, add flags, etc.).

[0320] At block 331 , the network later schedules one (L1 ) report on the CSI-RS belonging to the indicated SSB.

[0321] At block 332*, the UE indicates to the network the CSI index for which there is the highest probability of finding rank 4 by scheduling 2-port CSI simultaneously on each CSI index (the UE may send CSI-RS index, TCI index, add flags, etc.)

[0322] At block 333 , the network schedules 2-port CSI on the two indicated CSI beams.

[0323] At block 334, the UE measures and reports rank 4 in the CSI report.

[0324] At block 335, the network schedules layer 4 downlink MIMO.

[0325] At block 340, the UE is operating using layer 4 downlink MIMO.

[0326] UE 110 may signal the beam index(es) to be scheduled from the gNB to network 120, for example, to maximize the likelihood of obtaining rank 4.

[0327] Using network configuration, the network can configure the UE to report the preferred beam pair for achieving rank 4.

[0328] Using network configuration, the network may configure the UE to report which beam would be the preferred beam for achieving rank 4 if activated, in addition to the currently active beam.

[0329] For example, the UE is connected to CSI 1 and operates in rank 2. The network hopes to find the TCI state of rank 4.

[0330] According to one option, the network may configure the UE to report a preferred beam pair for achieving rank 4. The UE reports CSI 3 and CSI 4 as the best candidates for rank 4. Subsequently, the UE switches from CSI 1 to CSI 3 and CSI 4.

[0331] According to another option, the network may configure the UE to report which beam would be the preferred beam to achieve rank 4, if configured, in addition to the currently active beam.

[0332] In addition to the currently active TCI state, the gNB will also configure rank 4 TCI reporting for beams providing rank 4. In this case, the UE will report beam / CSI / TCI, for example, CSI 3, and the UE can then be controlled to operate with rank 4 on CSI 1 and CSI 3. The network does not have to switch the current TCI.

[0333] Thus, in some cases, the current TCI is reported as suitable for rank and remains unchanged to achieve rank 4; in other cases, the current TCI is reported as suitable for rank 4 in addition to another CSI (which may or may not be explicitly identified) to achieve rank 4 (in addition to the currently active CSI beam, the additional TCI beam can provide rank 4 when scheduled); in other cases, the current TCI is reported as unsuitable (alone or in combination with another CSI) to achieve rank 4.

[0334] The UE obtains information about the availability or unavailability of the rank using the indicator beam.

[0335] This reporting can be done in a number of ways:

[0336] Included in L1 of CSI report

[0337] Add flag on preferred beam for rank 4

[0338] Sort beams according to preferred beam for rank 4

[0339] New Rank 4 Dedicated L1 Report

[0340] New fields in CSI reports

[0341] Included in group-based beam reporting as a condition for rank 4

[0342] New Rank 4 Report

[0343] The signaled indication of the preferred beam(s) provided by the UE to the network may be one or both of the following options:

[0344] DL-RS index for rank 4 preferred beam(s)

[0345] The indication of the DL-RS index of the preferred beam can be absolute or relative to a reference beam. In other words, the UE can directly report the DL-RS index of the preferred beam or report the DL-RS index of a beam in the preferred beam, and

[0346] Reports the indices of the other beams relative to the reference beam.

[0347] For the latter case, for example, the UE may wish to report DL-RS indices {1, 2, 3, 4} as the preferred beam. The UE reports index 2 as the reference beam and reports the other beams as {-1, 1, 2}, which indicates the distance of the other indices to the reported reference index 2.

[0348] DL-RS index of the preferred beam for repetition

[0349] This indication may be used in cases where the beam pair does not provide sufficient channel diversity to achieve rank 4 but is still a good beam pair for simultaneous reception to improve robustness.

[0350] QCL TypeD relations for rank 4 preferred beam(s)

[0351] Therefore, the network can configure the RRC for the UE to report the index (options 1, 2) or the QCL relationship (option 3) or both (options 1+2+3), as well as dynamically change from one option to another. The UE can report the number of beam searches that can be reported for rank 4 (i.e., options 1, 2, 3, or all) in the capabilities.

[0352] At the UE, a cluster is defined as a set of taps (taps) separated in time based on the timestamp of each received signal. Two clusters are separated in time, they can be 2 (or more) groups of taps separated in time. The mapping of the 'same' cluster at the UE (i.e., cluster 1 in the PDP of UE identity CSI#y is also represented in the PDP of SSB#x) relies on overlapping timestamps, not received power levels. The UE also knows the receiving UE panel / beam and can separate what each UE panel / beam receives.

[0353] Case 1

[0354] In this case, the UE assesses that the two clusters detected in SSB#x beam are also found in CSI#y beam because the timestamps match (even though the power may be different due to different gNB beam gains). Therefore, in this case, the same CSI index and TCI state provide two clusters, so it is very likely that rank 4, i.e., 4-L DL MIMO, is found, which is likely from the 4-port CSI in the currently active TCI state.

[0355] Signaling option 1: CSI index indication from UE

[0356] Same CSI index and TCI status

[0357] Signaling Option 2: QCL information from UE

[0358] The CSI# beam of the 4 layers is QCL-TypeD

[0359] gNB actions:

[0360] The same CSI-RS may be configured with 4 ports in FR2, ie, two 2-port beams with the same Tx spatial filter for DL.

[0361] Case 2

[0362] In this case, the UE assesses that both clusters are part of the same SSB beam, but not the same CSI beam. The second cluster belongs to another CSI beam within the SSB beam. Therefore, 4-L DL MIMO is possible from 2×2-port CSI beams belonging to the same SSB spatial filter.

[0363] Signaling option 1: CSI index indication from UE

[0364] The UE indicates the CSI index / TCI state of two CSI beams of rank 4 (each with 2-port CSI-RS) that need to be scheduled simultaneously in order for the UE to search.

[0365] Signaling Option 2: QCL information from UE

[0366] Based on the example shown in Figure 4,

[0367] CSI#y and CSI#z are not QCL-TypeD, but

[0368] CSI#y and SSB#x are QCL-TypeD

[0369] CSI#z and SSB#x are QCL-TypeD

[0370] CSI#y is configured with 2 ports

[0371] CSI#z is configured with 2 ports

[0372] Case 3

[0373] In this case, the UE's assessment is that since the UE only sees a single cluster in an SSB, there is no point in searching for rank 4 in any CSI beam of that SSB beam. The gNB needs to combine two CSI beams belonging to different SSB beams to have a chance of finding rank 4. Therefore, the UE does not even need to compare with the PDP of CSI#y, since SSB#x already contains only a single cluster.

[0374] To find 4-L DL MIMO, the UE must find another cluster, i.e. from another SSB beam, and then select the best CSI beam within the second SSB

[0375] Signaling Option 1: UE CSI Index Indication

[0376] The UE indicates the SSB index where it needs to acquire the CSI-RS resources to find the second cluster

[0377] UE indications may include which SSBs should be detected (or excluded) from the search

[0378] Signaling Option 2: QCL information from UE

[0379] CSI#y and SSB#x are QCL-TypeD

[0380] The gNB needs to scan the CSI-RS of SSB#w to find, for example, CSI#m

[0381] CSI#m and SSB#w are QCL-TypeD

[0382] CSI#y and CSI#m are not QCL-TypeD

[0383] CSI#y is configured with 2 ports

[0384] CSI#m is configured with 2 ports

[0385] advantage:

[0386] Only 2 rounds of DL RS can find rank 4, as shown in the figure below (new indicators are in red):

[0387] Figure 11 Method 200 is illustrated in which UE 110 reports a preferred beam for rank 4 DL MIMO to network 120.

[0388] UE 110 sends UE capability report 201. This includes rank 4 beam searching report quantity. The UE indicates to the network its capabilities of what it can report. In some examples, the UE indicates to the network what it can report and how it can report.

[0389] For example, the indication of what it may report may indicate whether UE 110 may report candidate beams of a certain rank, or one or more ranks that the UE may report.

[0390] For example, the indication of what it may report may indicate whether it reports the beam by index or QCL, e.g., indicating the CSI index and / or the QCL configuration of the CSI beam.

[0391] The network may then configure UE 110 to perform specified reporting. This configuration may be, for example, an RRC configuration for reporting. The actual reporting may be layer one (L1) or medium access control (MAC).

[0392] UE 110 and network 120 are in RRC_Connected communication 203 .

[0393] The network 120 sends the UE an RRC configuration 205 for CSI reporting, including one (L1) beam measurement to be used later for SSB / CSI-RS.

[0394] This includes index and / or QCL relationship reporting.

[0395] Based on UE capabilities, the network has configured UE 110 to report the beams used to achieve rank (e.g., the beam pair that is most likely to achieve rank 4) when simultaneously scheduled. In this report, UE 110 may provide indexes and / or QCL information. For example, UE 110 may provide indices of candidate CSI beams and / or QCL relationships between candidate CSI beams.

[0396] The UE 11 uses 202 a data beam. The network sends a 2-port CSI-RS downlink reference signal 207. The UE responds with a CSI report 209 including information about the configured SSB / CSI-RS index, such as L1-RRP, L1-SINR, RI.

[0397] L1-RSRP is layer 1 reference signal received power.

[0398] L1-SINR is the layer 1 signal to interference and noise ratio.

[0399] RI is the rank indicator.

[0400] Following are the components of CSI in New Radio (NR):

[0401] CQI (Channel Quality Information)

[0402] PMI (Precoding Matrix Indicator)

[0403] CRI (CSI-RS Resource Indicator)

[0404] SSBRI (SS / PBCH Resource Block Indicator)

[0405] LI (Layer Indicator)

[0406] RI (Rank Indicator) and / or L1-RSRP

[0407] Based on the UE report 209 , the network selects 210 one or more CSI beams to try rank 4. The network 120 sends an RRC reconfiguration 211 of the CSI report to the UE 110 .

[0408] Network 120 transmits a 4-port CSI-RS for CSI#1 to UE 110. UE 110 uses 204 data beams.

[0409] The UE sends a CSI report 211 including an indication of a preferred beam for RI4 (rank indicator = rank 4). For example, the indication may be an index and / or a QCL relationship. The report corresponds to information 111.

[0410] Based on the UE report 215 , the network selects 212 one or more CSI beams to try for rank 4. The network 120 sends an RRC reconfiguration 217 of the CSI report to the UE 110 .

[0411] For example, the CSI ReportConfig sent by the network specifies which of the CSI ResourceConfigs to use for measurement. It includes an information element reportQuantity that determines what type of quantity (e.g., SSB RSRP, CQI, PMI, RI, etc.) the UE 110 should measure and report.

[0412] Network 120 sends 219 a 4-port CSI-RS for CSI #2 to UE 110. UE 110 uses 204 a data beam. The UE sends a CSI report 211 on CSI #2, including, for example, RI 4. The network configures 223 4-layer MIMO (PDSCH 4 layers of DL data, 4 layers in both cases of s-DCI or m-DCI operation).

[0413] The above concepts can be extended to multi-TRP scenarios.

[0414] In the above three cases, the UE either reports 1 CSI beam (in case 1) or reports 2 CSI beams (belonging to the same SSB beam in case 2, or belonging to different SSB beams in case 3), which are likely to support rank 4, that is, the UE reports the index / QCL relationship of 1 combination of (multiple) CSI beams with a high probability of supporting rank 4.

[0415] Obviously, the proposed idea can be generalized so that the UE can report an arbitrary number of combinations that it evaluates as having a high probability of supporting rank 4. In this case, the network:

[0416] Will try the first combination

[0417] If it does support rank 4, it will start sending rank 4 PDSCH using that first combination

[0418] If not, it will try the second combination

[0419] If the second combination actually supports rank 4, it will start sending rank 4 PDSCH using the second combination

[0420] If not, it will try the third combination.

[0421] This approach can be useful, for example, when more than 2 clusters are estimated in SSB, e.g.:

[0422] UE measures 3 clusters on SSB#x

[0423] UE measures 2 clusters (out of the 3 clusters) in CSI#y within SSB#x

[0424] UE measures another third cluster (of these 3 clusters) in CSI#z within SSB#x UE reports that it is very likely to support 2 combinations of rank 4

[0425] The first combination: CSI#y, with 4 ports

[0426] Second combination: CSI#y, with 2 ports, and CSI#z, with 2 ports This approach is also applicable to a large number of TRPs envisioned in future versions.

[0427] Figure 12 An example of method 350 is shown. It illustrates the process of generalizing the idea to >2 clusters (the details in the boxes of cases 1, 2, and 3 are the same as those in Figure 6 and will not be repeated)

[0428] At block 301 , the UE is in RRC_Connected and scheduled for 1 or 2 layers in downlink in 1TCI ​​state.

[0429] At block 302, the UE measures SS bursts and stores the PDP of the SSB with the best RESPR, eg, within 3 dB.

[0430] At block 303 , the UE measures the active TCI state (ie, CSI-RS) and stores the PDP, eg, 4 CSI-RS of the same SSB.

[0431] At block 304*, the UE compares the PDP of the SSB with the PDP of each CSI-RS.

[0432] At block 305*, the UE determines whether multiple clusters exist in the SSB PDP. If yes, the method moves to block 306, if not, the method moves to block 353 (case 3).

[0433] At block 306*, the UE determines whether more than one cluster in the SSB PDP exists in the PDP of the active CSI. If 'yes', the method moves to block 351 (case 1), and if 'no', the method moves to block 352 (case 2).

[0434] At block 351*, the UE indicates to the network that it has the highest probability of finding the target rank by scheduling multi-port CSI on the current active TCI state (the UE may send CSI-RS index, TCI index, add a flag, etc.). The network schedules multi-port CSI on the active TCI. The UE measures and reports the rank in the CSI report. The network schedules multi-layer downlink MIMO.

[0435] At block 352*, the UE indicates to the network the CSI index for which there is the highest probability of finding the target rank by simultaneously scheduling 2-port CSI on multiple CSIs (the UE may send CSI-RS index, TCI index, add a flag, etc.). The 2-port CSI is scheduled on multiple indicated CSI beams. The UE measures and reports the rank in the CSI report. The network schedules multi-layer downlink MIMO.

[0436] At block 353*, the UE indicates to the network the SSB index for which the CSI-RS may be scheduled so as to find the highest probability beam pair with rank 4 by simultaneously scheduling 2-port CSI on multiple CSIs (the UE may send the SSB index, TCI index, add a flag, etc.). The network schedules a layer one (L1) report on the CSI-RS belonging to the indicated SSB. The UE indicates to the network the CSI index for which there is the highest probability of finding rank 4 by simultaneously scheduling 2-port CSI on each of the CSI indexes (the UE may send the CSI-RS index, TCI index, add a flag, etc.).

[0437] The network schedules 2-port CSI on multiple indicated CSI beams. The UE measures and reports the rank in the CSI report. The network schedules multi-layer downlink MIMO.

[0438] At block 340, the UE is operating using layer 4 downlink MIMO.

[0439] Additional optional details for reports with >2 clusters:

[0440] Using 2 bits, the UE can identify up to 4 different clusters and is used to establish the relationship / mapping between TCI states (CSI beam / RS index) and different clusters. For example, the same bit combination for multiple TCI states will indicate that they can see the same cluster.

[0441] Note that in this example, we use the TCI index for mapping, but we can also use the DL-RS index for more general mapping.

[0442] For example, in the table below, TCI#1 and TCI#2 can see the same cluster, while TCI#3 and TCI#4 can see another cluster that TCI#1 and TCI#3 can see.

[0443] TCI#1 01 TCI#2 01 TCI#3 10 TCI#4 10

[0444] For example, in the table below, TCI#1, TCI#2, TCI#3, and TCI#4 can see the same cluster.

[0445] TCI#1 10 TCI#2 10 TCI#3 10 TCI#4 10

[0446] For example, in the table below, different clusters can be seen for TCI#1, TCI#2, TCI#3, and TCI#4.

[0447] TCI#1 00 TCI#2 01 TCI#3 10 TCI#4 11

[0448] List of abbreviations

[0449] 3GPP: Third Generation Partnership Project

[0450] CP: Cyclic Prefix

[0451] DCI: Downlink Control Information

[0452] DL: Downlink

[0453] DMRS: Demodulation Reference Signal

[0454] DUT: Device Under Test

[0455] FDM: Frequency Division Multiplexing

[0456] FFT: Fast Fourier Transform

[0457] FR: Frequency range

[0458] ICI: Inter-Carrier Interference

[0459] ISI: Inter-Symbol Interference

[0460] MIMO: Multiple Input Multiple Output

[0461] MRTD: Maximum Receive Timing Difference

[0462] MTTD: Maximum Transmission Timing Difference

[0463] NCJT: Non-coherent joint transmission

[0464] NR: New Radio

[0465] OFDM: Orthogonal Frequency Division Multiplexing

[0466] PDCCH: Physical Downlink Control Channel

[0467] PDSCH: Physical Downlink Shared Channel

[0468] PRB: Physical Resource Block

[0469] PTRS: Phase Tracking Reference Signal

[0470] PUCCH: Physical Uplink Control Channel

[0471] PUSCH: Physical Uplink Shared Channel

[0472] RS: Reference signal

[0473] RF: Radio Frequency

[0474] RTD: Receive Time Difference

[0475] SDM: Space Division Multiplexing

[0476] SINR: Signal to Interference and Noise Ratio

[0477] SNR: Signal-to-Noise Ratio

[0478] TA: Timing ahead

[0479] TCI: Transmission Configuration Indicator

[0480] TDM: Time Division Multiplexing

[0481] TRP: Transmission Reception Point

[0482] UE: User Equipment

[0483] UL: Uplink

[0484] Figure 13 An example of a method 500 is illustrated, the method comprising:

[0485] At block 503, information originating from a user equipment (UE) is received, the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE;

[0486] At block 504, UE-assisted assignment of one or more spatial transmit filters to data streams is performed based on the received information using at least one downlink transmission path that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

[0487] Figure 14 An example of a controller 400 suitable for use in an apparatus such as user equipment 110 or network node 120 is shown. An implementation of the controller 400 may be controller circuitry. The controller 400 may be implemented solely in hardware, have certain aspects in software including solely firmware, or may be a combination of hardware and software (including firmware).

[0488] like Figure 14 As shown, the controller 400 may be implemented using instructions that enable hardware functionality, for example, by using executable instructions of a computer program 406 in a general or special purpose processor 402, which instructions may be stored on a computer-readable storage medium (disk, memory, etc.) for execution by such processor 402.

[0489] The processor 402 is configured to read from and write to the memory 404. The processor 402 may also include an output interface via which data and / or commands are output by the processor 402 and an input interface via which data and / or commands are input to the processor 402.

[0490] The memory 404 stores a computer program 406, which includes computer program instructions (computer program code) that control the operation of the devices 110 and 120 when loaded into the processor 402. The computer program instructions of the computer program 406 provide the logic and routines that enable the apparatus to perform the methods shown in the accompanying drawings. The processor 402 can load and execute the computer program 406 by reading the memory 404.

[0491] The device 120 includes:

[0492] at least one processor 402; and

[0493] at least one memory 404 comprising computer program code,

[0494] The at least one memory stores instructions that, when executed by the at least one processor 402, cause the apparatus to at least:

[0495] storing information received from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE;

[0496] UE-assisted assignment of one or more spatial transmit filters to data streams is performed based on the received information using at least one downlink transmission path that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

[0497] The apparatus 110 includes:

[0498] at least one processor 402; and

[0499] at least one memory 404 comprising computer program code,

[0500] The at least one memory stores instructions that, when executed by the at least one processor 402, cause the apparatus to at least:

[0501] identifying, based on reception of downlink reference signals associated with the spatially independent downlink transmission paths at the time of transmission, at least a candidate downlink transmission path, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the time of reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path;

[0502] estimating a rank of a multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel;

[0503] The transmission of information identifying at least candidate downlink transmission paths and an estimated rank is caused.

[0504] like Figure 15 As shown, the computer program 406 may arrive at the apparatuses 110, 120 via any suitable delivery mechanism 408. The delivery mechanism 408 may be, for example, a machine-readable medium, a computer-readable medium, a non-transitory computer-readable storage medium, a computer program product, a memory device, a recording medium such as a compact disc read-only memory (CD-ROM) or a digital versatile disc (DVD) or a solid-state memory, or an article of manufacture that includes or tangibly embodies the computer program 906. The delivery mechanism may be a signal configured to reliably transmit the computer program 906. The apparatuses 110, 120 may propagate or transmit the computer program 906 as a computer data signal.

[0505] A computer program instruction is used to cause the device 120 to perform at least the following or to perform at least the following:

[0506] storing information received from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE;

[0507] UE-assisted assignment of one or more spatial transmit filters to data streams is performed based on the received information using at least one downlink transmission path that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

[0508] A computer program instruction is used to cause the apparatus 110 to perform at least the following items or to perform at least the following items:

[0509] identifying, based on reception of downlink reference signals associated with the spatially independent downlink transmission paths at the time of transmission, at least a candidate downlink transmission path, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the time of reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path;

[0510] estimating a rank of a multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel;

[0511] The transmission of information identifying at least candidate downlink transmission paths and an estimated rank is caused.

[0512] The computer program instructions may be included in a computer program, a non-transitory computer readable medium, a computer program product, a machine readable medium. In some, but not necessarily all, examples, the computer program instructions may be distributed across more than one computer program.

[0513] Although memory 404 is illustrated as a single component / circuitry, it may also be implemented as one or more separate components / circuitry, some or all of which may be integrated / removable and / or may provide permanent / semi-permanent / dynamic / cache storage.

[0514] Although processor 402 is illustrated as a single component / circuitry, it may also be implemented as one or more separate components / circuitry, some or all of which may be integrated / removable.Processor 402 may be a single-core or multi-core processor.

[0515] References to 'computer-readable storage medium', 'computer program product', 'tangibly embodied computer program', etc., or 'controller', 'computer', 'processor', etc. should be understood to encompass not only computers having different architectures, such as single / multi-processor architectures and sequential (von Neumann) / parallel architectures, but also special purpose circuits, such as field programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices, and other processing circuit systems. References to computer programs, instructions, code, etc. should be understood to encompass software for a programmable processor, or firmware, such as the programmable content of a hardware device, whether instructions for a processor or configuration settings for a fixed function device, gate array, or programmable logic device, etc.

[0516] As used in this application, the term 'circuitry' may refer to one or more or all of the following:

[0517] (a) Hardware circuit implementation only (such as implementation in analog and / or digital circuitry only)

[0518] as well as

[0519] (b) a combination of hardware circuitry and software such as (as applicable):

[0520] (i) a combination of analog and / or digital hardware circuit(s) and software / firmware, and (ii) any portion of hardware processor(s) (including digital signal processor(s)) with software, software, and memory(s) that work together to enable a device such as a mobile phone or server to perform various functions, and

[0521] (c) Hardware circuit(s) and / or processor(s), such as microprocessor(s) or portion(s) of microprocessor(s), that require software (e.g., firmware) to operate, but where software is not required for operation, the software may not be present.

[0522] This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As another example, as used in this application, the term "circuitry" also covers an implementation that is merely a hardware circuit or processor and its accompanying software and / or firmware. For example, if applicable to a particular claim element, the term "circuitry" also covers a baseband integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or networking equipment.

[0523] The blocks shown in the accompanying drawings may represent steps in a method and / or code segments 406 in a computer program. The illustration of a particular order of blocks does not necessarily indicate a required or preferred order for the blocks, and the order and arrangement of the blocks may vary. In addition, some blocks may be omitted.

[0524] As used herein, 'module' refers to a unit or device that does not include certain parts / components added by the final manufacturer or user.

[0525] The above example can be used as an enabling component for the following components:

[0526] Automotive systems; telecommunications systems; electronic systems, including consumer electronics; distributed computing systems; media systems for generating or rendering media content, including audio, video and audiovisual content and mixed, mediated, virtual and / or augmented reality; personal systems, including personal health systems or personal fitness systems; navigation systems; user interfaces, also known as human-machine interfaces; networks, including cellular, non-cellular and optical networks; ad-hoc networks; the Internet; the Internet of Things; virtualized networks; and related software and services.

[0527] According to examples of the present disclosure, the device can be provided in an electronic device, for example, a mobile terminal. However, it should be understood that the mobile terminal is merely an example of an electronic device that will benefit from examples of implementations of the present disclosure, and therefore, it should not be considered to limit the scope of the present disclosure to this. Although in some implementation examples, the device can be provided in a mobile terminal, other types of electronic devices, such as but not limited to: mobile communication devices, portable electronic devices, wearable computing devices, portable digital assistants (PDAs), pagers, mobile computers, desktop computers, televisions, gaming devices, laptop computers, cameras, video recorders, GPS devices, and other types of electronic systems can easily adopt examples of the present disclosure. In addition, devices can easily adopt examples of the present disclosure regardless of their intention to provide mobility.

[0528] The term 'comprise' is used in this document in an inclusive, rather than exclusive, sense. That is, any reference to X including Y indicates that X may include only one Y or may include more than one Y. If the exclusive meaning of 'comprise' is intended, this will be made clear in the context by reference to 'comprising only one' or by the use of 'consisting of.'

[0529] Throughout this specification, the terms "connected," "coupled," and "in communication with" and their derivatives refer to being operationally connected / coupled / in communication with one another. It should be understood that any number or combination of intermediary components (including no intermediary components) may be present, i.e., to provide direct or indirect connections / couplings / in communication with one another. Any such intermediary components may include hardware and / or software components.

[0530] As used herein, the term "determine" / "determining" (and grammatical variations thereof) may include at least: calculating, computing, processing, deriving, measuring, investigating, identifying, searching (e.g., searching in a table, a database, or another data structure), confirming, etc. Furthermore, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), obtaining, etc. Furthermore, "determine" / "determining" may include resolving, selecting, choosing, establishing, etc.

[0531] In this specification, reference is made to various examples. The description of features or functionality associated with an example indicates that those features or functionality are present in that example. The use of the term 'example' or 'for example' or 'may' or 'could' in the text indicates (whether or not explicitly stated) that such features or functionality are present in at least the example being described, whether or not described as an example, and that they may, but need not, be present in some or all other examples. Thus, 'example' or 'for example' or 'may' or 'could' refers to a particular instance within a class of examples. Attributes of an instance may be attributes of only that instance or attributes of a class or a subclass of a class that includes some but not all instances of the class. Thus, it is implicitly disclosed that features described with reference to one example but not with reference to another example may, where possible, be used as part of a working combination in that other example, but do not necessarily have to be used in that other example.

[0532] Although the examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims.

[0533] Features described in the preceding description may be used in other combinations than those explicitly described above.

[0534] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0535] Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not.

[0536] As used in this document, the terms 'a,' 'an,' or 'the' are intended to be inclusive, not exclusive. That is, unless the context clearly indicates otherwise, any reference to X that includes a / an / the Y means that X may include only one Y or may include more than one Y. If the exclusive meaning of 'a,' 'an,' or 'the' is intended, this will be made clear in the context. In some cases, 'at least one' or 'one or more' may be used to emphasize the inclusive meaning, but the absence of these terms should not be construed as inferring any exclusive meaning.

[0537] The presence of a feature (or combination of features) in a claim is a reference to that feature (or combination of features) itself, and also to features that achieve substantially the same technical effect (equivalent features). Equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same manner. Equivalent features include, for example, features that perform substantially the same function in substantially the same manner to achieve substantially the same result.

[0538] In this specification, reference is made to various examples using adjectives or adjective phrases to describe features of the examples. Such description of a characteristic associated with an example indicates that the characteristic exists in some examples exactly as described and in other examples substantially as described.

[0539] The above description describes some examples of the present disclosure, however, those skilled in the art will be aware of possible alternative structures and method features that provide equivalent functionality to the specific examples of such structures and features described above, and for the sake of brevity and clarity, these alternative structures and features have been omitted from the above description. Nevertheless, the above description should be understood to implicitly include reference to such alternative structures and method features that provide equivalent functionality, unless such alternative structures or method features are explicitly excluded in the above description of examples of the present disclosure.

[0540] While efforts have been made in the foregoing description to call attention to features regarded as important, it should be understood that the applicant may seek protection by way of claims for any patentable feature or combination of features mentioned above and / or shown in the drawings, whether or not emphasized.

Claims

1. A network node, comprising: means for receiving information originating from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE; Means for performing UE-assisted assignment of one or more spatial transmit filters to data streams to achieve at least rank 4 for UE multiple-input multiple-output (MIMO) using at least one downlink transmission path that is spatially independent at UE reception based on the received information.

2. The network node of claim 1 , wherein the UE-assisted assignment of the one or more spatial transmit filters to data streams provides multiple transmission paths that are spatially independent upon reception at the UE.

3. A network node according to claim 1 or 2, wherein the received information is an update to the network regarding the availability and / or unavailability of a rank using an indicator beam, wherein the indicator beam can be an existing beam, a currently active beam, or a currently inactive beam.

4. The network node according to any one of the preceding claims, wherein the received information comprises: An indication of an achievable rank using at least one spatially independent downlink transmission path that is spatially independent at reception at a UE.

5. The network node according to any one of the preceding claims, wherein identifying the received information of at least one spatially independent downlink transmission path that is spatially independent when received by a UE, identifying at least: candidate downlink transmission paths, the candidate downlink transmission paths being candidates for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent when received by the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path; and a rank for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the UE for reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel.

6. The network node according to any of the preceding claims, wherein the received information associates an achievable rank with a spatial transmit filter.

7. The network node according to any of the preceding claims, wherein the received information is used for UE directional downlink beam discovery for UE MIMO and to reduce the search space for possible spatial filters for UE MIMO.

8. The network node of claim 7, wherein UE directional downlink beam discovery for UE MIMO comprises: Transmitting an N*M port reference signal (or an N times M port reference signal) on an indicated beam of one or more allocated spatial transmit filters; as well as A rank report for the transmitted CSI-RS is received from the UE.

9. The network node of any preceding claim, wherein UE-assisted allocation of the one or more spatial transmit filters to data streams to achieve at least rank 4 for UE multiple-input multiple-output (MIMO) maximizes receive throughput at the UE.

10. The network node according to any one of claims 1 to 9, wherein the received information indicates: Availability of four receive ports for CSI-RS; and / or simultaneous availability of two receive ports for two CSI-RS.

11. The network node according to any one of claims 1 to 9, wherein the received information indicates: Candidate narrow beams for achieving rank N*M; or Candidate narrow beams for achieving rank N*M; or The rank N*M cannot be achieved using the candidate narrow beam within the identified wide beam (SSB), and the candidate narrow beam within the identified wide beam for achieving the rank M is indicated. 12 . The network node according to claim 11 , configured to use the candidate narrow beam for at least rank-N*M transmission or for rank-M transmission.

13. The network node according to any one of claims 1 to 10, The received information indicates: Candidate narrow beams for achieving rank 4; Candidate narrow beam pairs for achieving rank 4; Rank 4 cannot be achieved using the candidate narrow beam within the identified wide beam, and indicating the candidate narrow beam within the identified wide beam for achieving rank 2, or The received information indicates: One TCI / CSI for 4 layers; One TCI / CSI for 2 layers, or The received information indicates: A single CSI for achieving rank 4; or a candidate CSI pair for achieving rank 4 associated with the same SSB; or Candidate CSI associated with an SSB for achieving rank 2, where CSI in multiple SSBs is needed to achieve rank 4.

14. The network node according to any one of claims 1 to 9, wherein the received information indicates: i) The first SSB and the first CSI are QCL-Type D, ii) the first SSB and the first CSI are QCL-Type D, and the first SSB and the second CSI are QCL-Type D, iii) the first SSB and the first CSI are QCL-Type D, and the first SSB and the other CSI are not QCL-Type D, or The first SSB and the first CSI are QCL-TypeD, and the second SSB and the third CSI are QCL-TypeD.

15. A computer program comprising instructions which, when executed by a processor, cause: storing information received from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE; and performing UE-assisted assignment of one or more spatial transmit filters to data streams based on the received information using at least one downlink transmission path that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

16. A method comprising: receiving information originating from a user equipment (UE), the information identifying at least one spatially independent downlink transmission path that is spatially independent when received by the UE; and performing UE-assisted assignment of one or more spatial transmit filters to data streams based on the received information using at least one downlink transmission path that is spatially independent at UE reception to achieve at least rank 4 for UE multiple-input multiple-output (MIMO).

17. A user equipment (UE) comprising: means for receiving a downlink reference signal associated with a spatially independent downlink transmission path when transmitted; means for identifying at least a candidate downlink transmission path based on the receiving, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the UE reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path; means for estimating a rank of multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at the UE for reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel; Means for transmitting information identifying at least the candidate downlink transmission paths and the estimated rank.

18. The user equipment according to claim 17, configured to report to a network node a capability of identifying candidate downlink transmission paths and a rank for a multiple-input multiple-output (MIMO) of the UE, the candidate downlink transmission paths being candidates for the multiple-input multiple-output (MIMO) of the UE, the candidate downlink transmission paths comprising at least one candidate downlink transmission path.

19. The user equipment according to claim 17 or 18, configured to receive a communication from the network node indicating a target rank.

20. The user equipment according to any one of claims 17 to 19, wherein the means for identifying at least a candidate downlink transmission path based on the receiving comprises: means for determining the presence of one or more downlink transmission paths associated with a wide downlink beam; means for determining an association between the one or more downlink transmission paths associated with the wide downlink beam and one or more narrow downlink beams; wherein said means for transmitting information identifying at least said candidate downlink transmission paths and said estimated rank identifies said one or more narrow downlink beams.

21. The user equipment according to any one of claims 17 to 20, wherein the information is configured to identify whether a rank is available using a single candidate downlink transmission path or a rank is available using two downlink transmission paths.

22. The user equipment according to any one of claims 17 to 21, wherein the information is configured to: identify that a rank is unavailable using one or more downlink transmission paths in the set of downlink transmission paths associated with the wide downlink beam.

23. The user equipment according to any one of claims 17 to 22, wherein, according to the information QCL report received from the network node, the downlink beam associated with the one or more downlink transmission paths and the one or more narrow beams associated with the one or more downlink transmission paths are quasi-co-located Type D.

24. A computer program comprising instructions which, when executed by a processor, cause: identifying, based on reception of downlink reference signals associated with the spatially independent downlink transmission paths at the time of transmission, at least a candidate downlink transmission path, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the time of reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path; estimating a rank of a multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at the UE for reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel; Information identifying at least the candidate downlink transmission path and the estimated rank is transmitted.

25. A method comprising: identifying, based on reception of downlink reference signals associated with the spatially independent downlink transmission paths at the time of transmission, at least a candidate downlink transmission path, the candidate downlink transmission path being a candidate for UE multiple-input multiple-output (MIMO) using multiple simultaneous downlink transmission paths that are spatially independent at the time of reception at the UE, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission path; estimating a rank of a multiple-input multiple-output (MIMO) for a UE using multiple simultaneous downlink transmission paths that are spatially independent at the UE for reception, the multiple simultaneous downlink transmission paths including at least one candidate downlink transmission channel; Information identifying at least the candidate downlink transmission path and the estimated rank is transmitted.

Images