CSI Reporting Based on Linear Combination Codebook

Abstract

A method performed by a UE for generating a CSI report in a wireless communication system, including receiving from a network node, a CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set; identifying a precoding vector matrix for each transmission layer based on the first basis set, a second basis set comprising P basis vectors, and a number of combining coefficients for combining selected vectors from the first and second basis set; generating a CSI report based on the CSI report configuration information for a RI, or v of the rank set; and transmitting the CSI report to the network node.

Claims

1. A method performed by a user equipment (UE) for generating a channel state information (CSI) report in a wireless communication system, the method comprising: receiving from a network node, a CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands; identifying a precoding vector or matrix for each transmission layer based on the first basis set, a second basis set comprising P basis vectors, and a number of combining coefficients for combining selected vectors from the first and second basis sets; generating a CSI report based on the CSI report configuration information for a rank indication value (RI) or v of the rank set, wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, wherein the rank set comprises a first rank set and a second rank set, and the CSI report configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set, wherein D<D.sub.0 or DD.sub.0 when the rank value v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set; and transmitting the CSI report to the network node.

2. The method according to claim 1, wherein the CSI report comprises K.sub.1 combining coefficients per layer, wherein K.sub.1 is selected from K.sub.0 combining coefficients, and wherein K.sub.1 is reported by the UE.

3. The method according to claim 1, wherein the CSI report comprises K.sub.1 combining coefficients across all layers, wherein K.sub.1 is selected from 2K.sub.0 combining coefficients, and wherein K.sub.1 is reported by the UE.

4. The method according to claim 1, wherein the number of selected basis vectors, P.sub.l, from the second basis set per transmission layer satisfies a sum constraint across all RI transmission layers, wherein the total number of basis vectors selected from the second basis set across all layers is smaller or equal than a value, R, with R being a positive integer.

5. The method according to claim 1, wherein the CSI report comprises at least two parts, CSI part 1 and CSI part 2, wherein the first part, CSI part 1, has a fixed payload size and indicates the size of second part, CSI part 2, and CSI part 1 comprises an indication of the total number of selected basis vectors from the second basis set across all layers of the precoding vector or matrix.

6. The method according to claim 1, wherein the UE is configured to determine a common basis set comprising at least the selected basis vectors from the second basis set across all RI transmission layers, and to indicate the basis vectors of the common basis set and the basis vectors selected from the common basis set for each transmission layer of the precoding vector or matrix in the CSI report.

7. The method according to claim 1, wherein the basis vectors of the second basis set are grouped into B basis subsets, wherein each basis subset comprises a number of basis vectors, and the UE is configured to select b.sub.l basis subsets out of the B basis subsets per layer for the precoding vector or matrix and to indicate the selected b.sub.l basis subsets in the CSI report.

8. The method according to claim 7, wherein the UE is configured to select a number of basis vectors per layer within each selected basis subset and to indicate the selected basis vectors in the CSI report.

9. A method performed by a network node for receiving a channel state information (CSI) report generated by a user equipment (UE) in a wireless communication system, the method comprising: sending, to the UE, CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands; and receiving the CSI report from the UE, wherein the CSI report is based on the CSI report configuration information for a rank indication, value, RI, or v of the rank set, and wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, wherein the rank set comprises a first rank set and a second rank set, and the CSI report configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set, wherein D<D.sub.0 or DD.sub.0 when the rank value v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set.

10. A user equipment (UE) in a wireless communication system adapted to generate a channel state information (CSI) report, the UE being enabled to: receive from a network node, like a base station, CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands; identify a precoding vector or matrix for each transmission layer based on the first basis set, a second basis set comprising P basis vectors, and a number of combining coefficients for combining selected vectors from the first and second basis sets; generate a CSI report based on the CSI report configuration information for a rank value RI or v of the rank set, wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, wherein the rank set comprises a first rank set and a second rank set, and the CSI report configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set, wherein D<D.sub.0 or DD.sub.0 when the rank value v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set; and transmit the CSI report to the network node.

11. A user equipment (UE) comprising a processor and a memory, said memory containing instructions executable by said processor whereby said UE is operative to: receive from a network node, a channel state information (CSI) report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands; identify a precoding vector or matrix for each transmission layer based on the first basis set, a second basis set comprising P basis vectors, and a number of combining coefficients for combining selected vectors from the first and second basis sets; generate a CSI report based on the CSI report configuration information for a rank indication value (RI) or v of the rank set, wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, wherein the rank set comprises a first rank set and a second rank set, and the CSI report configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set, wherein D<D.sub.0 or DD.sub.0 when the rank value v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set; and transmit the CSI report to the network node.

12. A network node comprising a processor and a memory, said memory containing instructions executable by said processor whereby said network node is operative to: send, to the user equipment (UE), channel state information (CSI) report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands; and receive the CSI report from the UE, wherein the CSI report is based on the CSI report configuration information for a rank indication, value, RI, or v of the rank set, and wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, wherein the rank set comprises a first rank set and a second rank set, and the CSI report configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set, wherein D<D.sub.0 or DD.sub.0 when the rank value v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set.

13. A non-transitory computer-readable medium having stored thereon computer program instructions, which, when executed by a computer of a user equipment (UE) for generating a channel state information (CSI) report in a wireless communication system, cause the computer to: receive from a network node, a CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands; identify a precoding vector or matrix for each transmission layer based on the first basis set, a second basis set comprising P basis vectors, and a number of combining coefficients for combining selected vectors from the first and second basis sets; generate a CSI report based on the CSI report configuration information for a rank indication value (RI) or v of the rank set, wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, wherein the rank set comprises a first rank set and a second rank set, and the CSI report configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set, wherein D<D.sub.0 or DD.sub.0 when the rank value v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set; and transmit the CSI report to the network node.

14. The non-transitory computer-readable medium according to claim 13, wherein the computer program instructions cause the computer to determine a common basis set comprising at least the selected basis vectors from the second basis set across all RI transmission layers, and indicate the basis vectors of the common basis set and the basis vectors selected from the common basis set for each transmission layer of the precoding vector or matrix in the CSI report.

15. The non-transitory computer-readable medium according to claim 13, wherein the basis vectors of the second basis set are grouped into B basis subsets, wherein each basis subset comprises a number of basis vectors, and wherein the computer program instructions cause the computer to select b.sub.l basis subsets out of the B basis subsets per layer for the precoding vector or matrix and to indicate the selected b.sub.l basis subsets in the CSI report.

16. A non-transitory computer-readable medium having stored thereon computer program instructions, which, when executed by a computer of a network node for receiving a channel state information (CSI) report generated by a user equipment (UE) in a wireless communication system, cause the computer to: send, to the UE, CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands; and receive the CSI report from the UE, wherein the CSI report is based on the CSI report configuration information for a rank indication, value, RI, or v of the rank set, and wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, wherein the rank set comprises a first rank set and a second rank set, and the CSI report configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set, wherein D<D.sub.0 or DD.sub.0 when the rank value v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments of the present invention are now described in further detail with reference to the accompanying drawings, in which:

[0028] FIG. 1A shows a schematic representation of a wireless communication system;

[0029] FIG. 1B shows a cell-based representation of a wireless communication system;

[0030] FIG. 2 shows a block-based model of a MIMO DL transmission using codebook-based-precoding in accordance with LTE release 8;

[0031] FIG. 3 is a schematic representation of a wireless communication system for communicating information between a transmitter, which may operate in accordance with the inventive teachings described herein, and a plurality of receivers, which may operate in accordance with the inventive teachings described herein;

[0032] FIG. 4 is a schematic representation of a radio base station; and

[0033] FIG. 5 is a schematic representation of a user equipment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] In the following, preferred embodiments of the present invention are described in further detail with reference to the enclosed drawings in which elements having the same or similar function are referenced by the same reference signs.

[0035] Embodiments of the present invention may be implemented in a wireless communication system or network as depicted in FIG. 1A or 1B, or FIG. 2 including transmitters or transceivers, like base stations, and communication devices (receivers) or users, like mobile or stationary terminals or IoT devices, as mentioned above. FIG. 3 is a schematic representation of a wireless communication system for communicating information between a transmitter 200, like a base station, and a plurality of communication devices 202.sub.1 to 202.sub.n, like UEs, which are served by the base station 200. The base station 200 and the UEs 202 may communicate via a wireless communication link or channel 204, like a radio link. The base station 200 includes one or more antennas ANT.sub.T or an antenna array having a plurality of antenna elements, and a signal processor 200a. The UEs 202 include one or more antennas ANT.sub.R or an antenna array having a plurality of antennas, a signal processor 202a.sub.1, 202a.sub.n, and a transceiver 202b.sub.1, 202b.sub.n. The base station 200 and the respective UEs 202 may operate in accordance with the inventive teachings described herein.

Method

[0036] The present invention provides a method for providing feedback about a MIMO channel between a transmitter and a receiver in a wireless communication system according to the present invention.

Computer Program Product

[0037] The present invention provides a computer program product comprising instructions which, when the program is executed by a computer, causes the computer to carry out one or more methods in accordance with the present invention.

User Equipment

[0038] The present invention provides a user equipment apparatus in a wireless communication system, the user equipment is configured to generate a channel state information, CSI, report for providing feedback about a MIMO channel between a network node and the user equipment in the wireless communication system, according to the present invention.

[0039] The present invention proposes the use of a user equipment, UE, comprising a processor and a memory, which memory contains instructions executable by the processor whereby the UE is operative to perform any one of the subject-matter of the inventive method relating to a method performed by a user equipment.

Network Node

[0040] The present invention proposes the use of a network node comprising a processor and a memory, which memory contains instructions executable by the processor whereby the network node is operative to perform any one of the subject-matter of the inventive method relating to a method performed by a network node.

System

[0041] The present invention provides a wireless communication system operated in accordance with the inventive method. Further, the present invention provides a wireless communication system including one or more of the inventive receivers and/or one or more of the inventive transmitters.

[0042] In accordance with embodiments, the transmitter and/or the receiver mentioned above may include one or more of the following: a UE, or a mobile terminal, or a stationary terminal, or a cellular IoT-UE, or a vehicular UE, or a vehicular group leader (GL) UE, or an IoT, or a narrowband IoT, NB-IoT, device, or a WiFi non Access Point STAtion, non-AP STA, e.g., 802.11ax or 802.11be, or a ground based vehicle, or an aerial vehicle, or a drone, or a moving base station, or a road side unit, or a building, or any other item or device provided with network connectivity enabling the item/device to communicate using the wireless communication network, e.g., a sensor or actuator, or a macro cell base station, or a small cell base station, or a central unit of a base station, or a distributed unit of a base station, or a relay, or a remote radio head, or an AMF, or an SMF, or a core network entity, or mobile edge computing entity, or a network slice as in the NR or 5G core context, or any transmission/reception point, TRP, enabling an item or a device to communicate using the wireless communication network, the item or device being provided with network connectivity to communicate using the wireless communication network.

[0043] One proposed embodiment of the present invention relates to a method for providing feedback about a MIMO channel between a transmitter, like a network node, e.g., a gNB, and a receiver, like a UE, in a wireless communication system described in the following steps.

[0044] In a step S11, the UE is provided from a network node with a CSI report configuration via a higher layer (e.g., RRC), the CSI report configuration indicating a number of antenna ports or CSI-RS ports. An antenna port, or simply port, is a CSI-RS port. In the following antenna port, port and CSI-RS port are interchangeably used. The one or more antenna ports are associated with one or more reference signals. The CSI report configuration information also includes at least one parameter, D, for indicating a first basis set of D basis vectors used at the UE for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, wherein D<N.sub.3.

[0045] In step S12, the receiver receives a radio signal via the MIMO channel, wherein the radio signal includes the one or more reference signals, like one or more CSI-RS signal(s), which are associated with the antenna ports.

[0046] In a step S13, the receiver determines for each transmission layer a precoding vector or matrix based on the received radio signal, wherein the precoding vector or matrix to be used at the transmitter so as to achieve a predefined property for a communication over the MIMO channel. The precoding vector or matrix is determined based on the received reference signal(s) for a rank value RI or v of the rank set, a first basis set comprising D basis vectors, a second basis set comprising P basis vectors, and a number of combining coefficients or precoder coefficients for combining selected vectors from the first and second basis sets.

[0047] In a step S14, the receiver reports a feedback in the form of one or more CSI reports to the transmitter. The feedback indicates the precoding vector or matrix for each transmission layer determined by the receiver. The CSI report also comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set.

[0048] Another proposed embodiment of the present invention relates to a method performed by a user equipment, UE, for providing channel state information, CSI, feedback in the form of one or more CSI reports in a wireless communication system described in the following steps.

[0049] In a step S21, the UE receives from a network node a radio signal via a MIMO channel. The radio signal includes the CSI-RS signal(s) according to the one or more CSI-RS resource configuration(s). The CSI-RS signal(s) is/are provided over a configured number of frequency (and time) domain resources, and one or more antenna port(s) or one or more CSI-RS port(s).

[0050] In a step S22, the UE determines for each CSI report configuration a precoding vector or matrix for a number of antenna ports, subbands or resource blocks indicated by the CSI report configuration(s) based on the received downlink CSI-RS signals. The precoding vector or matrix is determined for each transmission layer based on the received reference signal(s), a first basis set comprising D basis vectors, a second basis set comprising P basis vectors, and a number of combining coefficients or precoder coefficients for combining selected vectors from the first and second basis sets.

[0051] In a step S23, the UE reports to the transmitter (network node) a Channel State Information, CSI, feedback, and/or a Precoder matrix Indicator, PMI and/or a PMI/Rank Indicator, PMI/RI, used to indicate the precoding matrix for the antenna ports selected by the UE from the configured antenna ports and subbands and/or resource blocks. The CSI feedback, or the PMI as a part of the CSI feedback, includes for each transmission layer or subsets of transmission layers or all transmission layers of the precoding vector or matrix an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set.

[0052] It is noted that the steps S11, S12, S13, S14 and S21, S22, S23 of the methods described above also represent a description of a corresponding block or feature of a corresponding apparatus, e.g., the corresponding base station, like base station 200 described with reference to FIG. 2 or FIG. 3, or the corresponding UE, like UE 202 described with reference to FIG. 2 or FIG. 3.

Codebook-Based Precoder Structure

[0053] In accordance with embodiments, a user equipment for generating a channel state information, CSI, report in a wireless communication system, the UE comprising: [0054] receiving from a network node, like a base station, CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, each vector of size N.sub.31, wherein D<N.sub.3, and N.sub.3 is a number of subbands, [0055] identifying a precoding vector matrix for each transmission layer based on the first basis set, a second basis set comprising P basis vectors, and a number of combining coefficients for combining selected vectors from the first and second basis sets, [0056] generating a CSI report based on the CSI report configuration information for a rank value RI or v of the rank set, wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P selected basis vectors from the second basis set, wherein P<P or PP, and for each of the P basis vectors an indication of D<D or DD selected basis vectors from the first basis set, and [0057] transmitting the CSI report over an uplink channel.

[0058] In accordance with embodiments, the precoding vector for a transmission layer is based on a first basis set of D basis vectors, a basis set comprising P basis vectors wherein the vectors are selected from a second basis set of P basis vectors, each vector of size P1 or P/21, wherein P is a number of antenna ports or CSI-RS ports configured to the UE, and P<P or PP and N.sub.3 is a number of subbands or PRBs or frequency domain units/components used for PMI reporting configured to the UE or reported by the UE. The precoding vector or matrix W.sup.l for the l-th transmission layer may be defined by

[00012]$W^l=W_{1,l}{W}_{2,l}{W}_{f,l}^H,\mathrm{or}$$W^l={.Math.}_{p=0}^{P^{}-1}{.Math.}_{d=0}^{D-1}{c}_{l,p,d}\left(b_{l,p}{a}_{l,p,d}^H\right)={.Math.}_{d=0}^{D-1}{.Math.}_{p=0}^{P^{}-1}{c}_{l,p,d}\left(b_{l,p}{a}_{l,p,d}^H\right),\mathrm{or}$$W^l=\left[\begin{array}{c}{.Math.}_{p=0}^{P^{}-1}{.Math.}_{d=0}^{D-1}{c}_{l,p,d}\left(b_{l,p,d}{a}_{l,p,d}^H\right)\\ {.Math.}_{p=0}^{P^{}-1}{.Math.}_{d=0}^{D-1}{c}_{l,p+P^{},d}\left(b_{l,p,d}{a}_{l,p,d}^H\right)\end{array}\right],$

where [0059] W.sub.1,l is a matrix comprising P selected basis vectors from the second basis set, [0060] W.sub.2,l is a coefficient matrix,

[00013]$W_{f,l}^H$

is a matrix comprising D or less than D basis vectors from the first basis set, [0061] b.sub.l,p is a P1 vector or P/21 basis vector from the second basis set, [0062] a.sub.1,p,d is a N.sub.31 basis vector from the first basis set, and [0063] c.sub.l,p,d is a complex precoder coefficient or combining coefficient.
In accordance with embodiments, each basis vector from the first basis set is defined by an DFT-vector or IDFT-vector of size N.sub.31.

[0064] In accordance with embodiments, each basis vector from the second basis set is either of size P1 or P/21 and comprises a single one and zeros elsewhere. Hence, the second basis set comprising P basis vectors may be either defined by an identity matrix of size PP or an identity matrix of size P/2P/2. Moreover, when the second basis set is defined by an PP identity matrix, each basis vector from the second basis set is associated with a single antenna port and when the second basis set is defined by an P/2P/2 identity matrix, each basis vector from the second basis set is associated with two antenna ports, wherein the two antenna ports are associated with two different polarizations. In some examples, P/2 antenna ports are associated with a first polarization and P/2 antenna ports are associated with a second polarization.

[0065] The precoding vector or matrix for each transmission layer is based on P selected basis vectors from the second basis set, wherein the selection is polarization-common when each vector of the second basis set is associated with two antenna ports of different polarizations, and polarization-independent when each vector of the second basis set is associated with a single antenna port.

[0066] In accordance with embodiments, the columns of the precoding vector or matrix W.sup.l for l=0, . . . , v1 are normalized to norm one, wherein v denotes the overall rank of the transmission precoding vector or matrix.

[0067] In the following, a high-rank CSI reporting, whereinv>1 is considered. Here, v denotes the rank, or simply RI value, and indicates the number of layers of the precoding matrix indicated in the CSI report. The v layers of the precoding matrix are indicated as follows l=0,1,2, . . . , v1.

Number of Subbands:

[0068] In accordance with embodiments, the UE is configured to determine the dimension of the first basis set N.sub.3 based on the higher layer configuration parameter, number of CQI subbands N.sub.CQI, as N.sub.3=[QN.sub.CQI], where Q1 and Q is indicated in the CSI report by the UE.

In accordance with embodiments, the UE is configured to determine the dimension of the first basis set N.sub.3 based on the parameter Q and number of CQI subbands N.sub.CQI, as N.sub.3=[Q.Math.N.sub.CQI I], wherein the parameter Q is higher layer configured to the UE or known to the UE, e.g., fixed in the NR specification.

Configuration/Indication of Parameter D

[0069] In accordance with embodiments, the UE is configured to receive a CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set or a layer set, wherein the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, wherein D<N.sub.3.

[0070] In one exemplary embodiment, one of the following sets may define the rank set: I{1}RI {1,2}, RI{2,3,4}, RI{3,4} or RI {1,2,3,4}, wherein RI denotes the rank of the precoder vector or matrix. In the following RI and v are interchangeably used.

[0071] In one exemplary embodiment, one of the following sets may define the layer set: l{0}, l{0,1}, l{1,2,3}, l{2,3} or l{0,1,2,3}, wherein l denotes the index for a layer of the precoder vector or matrix.

[0072] In accordance with embodiments, the rank set comprises a first rank set and a second rank set, and the CSI reporting configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first rank set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second rank set. In one example, the first rank set is defined by RI{1,2} and the second rank set is defined by RI{3,4}. In another example, the first rank set is defined by RI{1} and the second rank set is defined by RI{2,3,4}. In another example, the first rank set is defined by RI{1,2,3} and the second rank set is defined by RI{4}.

[0073] In accordance with embodiments, the layer set comprises a first layer set and a second layer set, and the CSI reporting configuration information comprises at least one parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the first layer set and at least one parameter D.sub.1 for indicating D.sub.1 basis vectors for the first basis set for the second layer set. In one example, the first layer set is defined by l{0,1} and the second layer set is defined by l{2,3}. In another example, the first layer set is defined by l{0} and the second layer set is defined by l{1,2,3}. In another example, the first layer set is defined by l{0,1,2} and the second layer set is defined by l{3}.

[0074] In accordance with embodiments, the UE is configured to select D basis vectors from the first basis set, wherein D<D.sub.0 or DD.sub.0 when the rank RI or v of the precoding vector or matrix belongs to the first rank set and D<D.sub.1 or DD.sub.1 when the rank value v of the precoding vector or matrix belongs to the second rank set.

[0075] In accordance with embodiments, the UE is configured to select D basis vectors from the first basis set, wherein D<D.sub.0 or DD.sub.0 when a layer of the precoding vector or matrix belongs to the first layer set and D<D.sub.1 or DD.sub.1 when a layer of the precoding vector or matrix belongs to the second layer set.

[0076] In accordance with embodiments, the CSI reporting configuration information comprises a parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the rank set, and a parameter D.sub.1, indicating D.sub.1 basis vectors for the first basis set for another rank set, is derived by the UE at least from the parameter D.sub.0.

[0077] In accordance with embodiments, the CSI reporting configuration information comprises a parameter D.sub.0 for indicating D.sub.0 basis vectors for the first basis set for the layer set, and a parameter D.sub.1, indicating D.sub.1 basis vectors for the first basis set for another layer set, is derived by the UE at least from the parameter D.sub.0.

[0078] In accordance with embodiments, the UE is configured to select D basis vectors from the first basis set, wherein D<D.sub.0 or DD.sub.0 when the rank value RI or v of the precoding vector or matrix belongs to the rank set, and D<D.sub.1 or DD.sub.1 when the rank value RI or v of the precoding vector or matrix belongs to the another rank set.

[0079] In accordance with embodiments, the UE is configured to select D basis vectors from the first basis set, wherein D<D.sub.0 or DD.sub.0 when a layer of the precoding vector or matrix belongs to the layer set, and D<D.sub.1 or DD.sub.1 when a layer of the precoding vector or matrix belongs to the another layer set.

[0080] In accordance with embodiments, the number of basis vectors, D, of the first basis set are indicated to the UE, determined by the UE (e.g., the parameter D is fixed in the NR specifications), or reported by the UE. In an exemplary embodiment, the parameter D is indicated to the UE via a higher layer configuration (e.g., the CSI report configuration) from the network node.

[0081] In one exemplary embodiment, the number of basis vectors, D.sub.0, of the first basis set depends on the layer index or layer-group index, wherein D.sub.0 is configured to the UE for a first layer set comprising one or more layers (e.g., a first layer or a first layer and a second layer), and the parameter D.sub.1 for a second layer set comprising one or more layers (e.g., a second layer, or a third layer, or a third and fourth layer) is determined and reported by the UE as a part of the CSI report, or configured to the UE.

[0082] In one exemplary embodiment, the parameter D is smaller than N.sub.3, i.e., D<N.sub.3, where N.sub.3 is a number of subbands, PRBs or frequency domain units/components used for PMI reporting configured to the UE or reported by the UE. Hence, the first basis set used for constructing the precoding vector or matrix may be defined by a proper submatrix of size DN.sub.3 of a DFT-matrix or IDFT-matrix of size N.sub.3N.sub.3, wherein each vector of the first basis set is represented by an DFT- or IDFT-vector (of size N.sub.31). In another exemplary embodiment, the parameter is D=N.sub.3. Then, the first basis set is defined by an full DFT-matrix or IDFT-matrix of size N.sub.3N.sub.3, and each vector of the first basis set is represented by an DFT- or IDFT-vector (of size N.sub.31).

[0083] In an exemplary embodiment, the parameter D (indicating the number of basis vectors of the first basis set) depends on the layer index, or on the layer-group index and is decreasing or increasing with increasing layer indices or layer group indices. In one example, for RI=4, D=1 for the first layer, D=2 for the second layer, D=3 for the third layer, and D=5 for the fourth layer. In one example, for RI=4, D=1 for the first layer-group comprising the first layer and second layer, and D=3 for the second layer-group comprising the third layer and fourth layers. In one example, for RI=3, D=1 for the first layer-group comprising the first layer and second layer, and D=3 for the second layer-group comprising the third layer. In one example, for RI=2, D=1 for the first layer-group comprising the first layer and second layer. In one example, for RI=1, D=1 for the first layer-group comprising only the first layer. In one example, for RI=4, D=4 for the first layer, D=3 for the second layer, D=2 for the third layer, and D=1 for the fourth layer. In one example, for RI=4, D=4 for the first layer-group comprising the first layer and second layer, and D=2 for the second layer-group comprising the third layer and fourth layers. In one example, for RI=3, D=2 for the first layer-group comprising the first layer and second layer, and D=1 for the second layer-group comprising the third layer. In one example, for RI=2, D=2 for the first layer-group comprising the first layer and second layer.

[0084] In accordance with embodiments, when D=1 (e.g., for a layer, subset of layers or all layers) the first basis set comprises a single vector wherein all elements of the vector are 1s.

[0085] In an exemplary embodiment, the parameter D (indicating the number of basis vectors of the first basis set) depends on the layer index, or on the layer-group index and is configured to the UE for at least one layer-group set (e.g., layer indices l=0,1) and reported by the UE for at least another layer group set (e.g., layer indices l=2,3). Here a layer-group set may comprise at least one layer index. Note that the layer indices of the layer-group sets can be different to each other. This means when there are at least two layer-groups, the layer indices of the first layer-group set can be different to the layer indices of the second layer-group set.

[0086] In an exemplary embodiment, the parameter D (indicating the number of basis vectors of the first basis set) depends on the layer index, or on the layer-group index and is fixed in the NR specifications for at least one layer-group set (e.g., a set comprising layer indices l=0,1), and determined and reported by the UE for at least one another layer group set (e.g., a set comprising layer indices l=2,3). The parameter D (and hence the number of basis vectors of the first basis set) for at least one first layer-group set is either explicitly specified in the NR specifications, or determined from at least one other parameter configured to the UE. Here a layer-group set may comprise at least one layer index. Note that the layer or layer indices of the layer-group sets can be different to each other. This means when there are at least two layer-groups, the layer indices of the first layer-group set can be different to the layer indices of the second layer-group set.

[0087] In one exemplary embodiment, the parameter D (indicating the number of basis vectors of the first basis set) is RI-common for v{1,2,3,4} or RI{1,2,3,4} and layer-common. This means, a single parameter D (and hence the number of basis vectors of the first basis set) is used for all layers l=0,1,2, . . . , v1 and for all RI values v{1,2,3,4}. The parameter D may be configured to the UE, determined by the UE (e.g., using one or more other parameters such as the RI value), reported by the UE, or is known by the UE, e.g., the parameter D is defined in the NR specifications.

[0088] In one exemplary embodiment, the parameter D (indicating the number of basis vectors of the first basis set) is RI-common for v{1,2,3,4} or RI{1,2,3,4} and layer-specific or layer-group-specific. This means, a single parameter D (and hence the number of basis vectors of the first basis set) is used for each layer l=0,1,2, . . . , v1 or subset of layers (e.g., l=0,1, and l=2,3) for all RIs v{1,2,3,4}. The parameter D can be different for each layer or subsets of layers. For example, the parameter D may depend on the layer-index or layer-group-index, but it does not depend on the RI value. Hence, one or more parameter(s) D (for each layer or subsets of layers) may be configured to the UE, determined by the UE (e.g., using one or more other parameters such as the RI value), reported by the UE, or is/are known by the UE, e.g., the one or more parameter(s) D may be defined in the NR specifications.

[0089] In one exemplary embodiment, the parameter D (indicating the number of basis vectors of the first basis set) is RI-common for a rank set, e.g., v{2,3,4} or v{3,4}, and layer-common. This means, a single parameter D (and hence the number of basis vectors of the first basis set) is used for all layers l=0,1,2, . . . , v1 and for all RI values of the rank set v{2,3,4} or v{3,4}. The parameter D may be configured to the UE, determined by the UE (e.g., using one or more other parameters such as the RI value), reported by the UE, or it is known by the UE, e.g., the parameter D is defined in the NR specifications.

[0090] In one exemplary embodiment, D (indicating the number of basis vectors of the first basis set) is RI-common for a rank set, e.g., v{2,3,4} or v{3,4}, and layer-specific or layer-group-specific. This means, a single parameter D is used for each layer l=0,1,2, . . . , v1 or subsets of layers (e.g., l=0,1, and l=2,3) for all for all RI values of the rank set v{2,3,4} or v{3,4}. The parameter D (and hence the number of basis vectors of the first basis set) can be different for each layer or subsets of layers. Hence, one or more parameter(s) D may be configured to the UE, determined by the UE (e.g., using one or more other parameters such as the RI value), reported by the UE, or known by the UE, e.g., the one or more parameter(s) D may be defined in the NR specifications.

[0091] In one exemplary embodiment, the parameter D (indicating the number of basis vectors of the first basis set) is RI-specific for a rank set, e.g., v{2,3,4} or v{3,4}, and layer-common. This means, a single parameter D (and hence the number of basis vectors of the first basis set) is used for each RI value or for subsets of RI values from the rank set. The parameter D is identical for all layers l=0,1,2, . . . , v1 for a given RI value v, but it can be different for each RI value or subsets of RI values. Hence, one or more parameter(s) D (for each layer or subsets of layers) may be configured to the UE, determined by the UE (e.g., using one or more other parameters such as the RI value), reported by the UE, or known by the UE, e.g., the one or more parameter(s) D may be defined in the NR specifications.

[0092] In one exemplary embodiment, D (indicating the number of basis vectors of the first basis set) is RI-specific for a rank set, e.g., v{2,3,4} or v{3,4}, and layer-specific or layer-group-specific. This means, a single parameter D (and hence number of basis vectors of the first basis set) is used for each RI value or subset of RI values and layer or subset of layers. The parameter K can be different for all layers l=0,1,2, . . . , v1 or subset of layers for a given RI value v from the rank set. Hence, one or more parameter(s) D (for each layer or subsets of layers) may be configured to the UE, determined by the UE (e.g., using one or more other parameters such as the RI value), reported by the UE, or known by the UE, e.g., the one or more parameter(s) D may be defined in the NR specifications.

[0093] In one exemplary embodiment, the parameter D is RI-common for a rank set, e.g., RI{1,2} or RI{3,4}, wherein a single parameter D for all layers is configured to the UE, determined by the UE (e.g., using one or more other parameters such as the RI value), reported by the UE, or known by the UE, e.g., the parameter D is defined in the NR specifications.

[0094] Note that in the above examples, a rank set may comprise a subset of N RI values from the set RI{1,2,3,4}, wherein N2 or N<4.

[0095] In one exemplary embodiment, the number of basis vectors of the first basis set is RI-common for a first rank set, wherein a single parameter D.sub.0, indicating the number of basis vectors of the first basis set for all layers of the precoder vector or matrix, is configured to the UE, and the number of basis vectors of the first basis set is RI-common for a second rank set, wherein a single parameter D.sub.1, indicating the number of basis vectors of the first basis set for all layers of the precoder vector or matrix, is determined by the UE (e.g., by a fixed rule based on the RI value), or configured to the UE, or reported by the UE. The RI values of the first rank set may be different to the RI values of the second rank set. In one example, the first rank set is given by RI{1} and the second rank set is given by RI{2,3,4}. In another example, the first rank set is given by RI{1,2} and the second rank set is given by RI{3,4}. In another example, the first rank set is given by RI{1,2,3} and the second rank set is given by RI{4}.

[0096] In one exemplary embodiment, the number of basis vectors of the first basis set is RI-common for a first rank set, wherein one or more parameter(s) D.sub.0, indicating the number of basis vectors of the first basis set for subsets of layers of the precoder vector or matrix, is configured to the UE, and the number of basis vectors of the first basis set is RI-common for a second rank set, wherein one or more parameter(s) D.sub.1, indicating the number of basis vectors of the first basis set for subsets of layers of the precoder vector or matrix, is determined by the UE (e.g., by a fixed rule based on the RI value), configured to the UE, or reported by the UE. Here, a subset of layers may comprise all RI layers or less than RI layers for each rank of the rank set. The RI values of the first rank set may be different to the RI values of the second rank set. In one example, the first rank set is given by RI{1} and the second rank set is given by RI{2,3,4}. In another example, the first rank set is given by RI{1,2} and the second rank set is given by RI{3,4}. In another example, the first rank set is given by RI{1,2,3} and the second rank set is given by RI{4}.

[0097] Note that in the above examples, a layer subset may comprise N layer indices from the set of l{0,1, . . . , v1} layer indices, wherein Nv or N<v.

In accordance with embodiments, the basis vectors of the first basis set is a subset of a basis set comprising N.sub.3 basis vectors, wherein D<N.sub.3, and wherein the D basis vectors of the first basis set are given by the first D basis vectors of the basis set containing N.sub.3 basis vectors. In one option, the basis set comprises a N.sub.3N.sub.3 DFT based matrix [a.sub.0, a.sub.1, . . . a.sub.N.sub.31] and the first basis set comprises the D basis vectors (a.sub.0, . . . , a.sub.D1).
In one example, the D basis vectors of the first basis set are given by the first D.sub.a basis vectors and the last D.sub.b basis vectors of the basis set containing N.sub.3 basis vectors, wherein D.sub.a+D.sub.b=D. In one option, the basis set comprises a N.sub.3N.sub.3 DFT based matrix comprising basis vectors [a.sub.0, a.sub.1, . . . a.sub.N.sub.31] and the first basis set comprises the D basis vectors (a.sub.0, . . . , a.sub.D.sub.a1, a.sub.N.sub.3.sub.D.sub.b, . . . , a.sub.N.sub.31).

[0098] In another example, the D basis vectors of the first basis set are given by the D basis vectors associated with the indices a.sub.i, i=0, . . . , D1 from the basis set containing N.sub.3 basis vectors where a.sub.i=mod(a.sub.s+i,N.sub.3), i=0, . . . , D1, and wherein as is the starting index of the basis vector from the basis set containing N.sub.3 basis vectors. In one option, the basis set comprises a N.sub.3N.sub.3 DFT based matrix comprising basis vectors [a.sub.0, a.sub.1, . . . a.sub.N.sub.31] and the first basis set comprises the D basis vectors (d.sub.0, . . . d.sub.D1)=(a.sub.mod(a.sub.s.sub.+0,N.sub.3.sub.), . . . , a.sub.mod(a.sub.s.sub.+D1,N.sub.3.sub.)).

[0099] In another example, the D basis vectors of the first basis set are given by the D basis vectors associated with the indices a.sub.i.sub.n, i.sub.n=0, . . . , D.sub.n1, n=0 . . . N1 from the basis set containing N.sub.3 basis vectors where a.sub.i.sub.n=mod(a.sub.s.sub.n+i.sub.n, N.sub.3), i.sub.n=0, . . . , D.sub.n1, wherein a.sub.s.sub.n is the starting index of the basis vector from the basis set containing N.sub.3 basis vectors for the window n, and wherein

[00014]${.Math.}_{n=0}^{N-1}{D}_n=D$

and wherein a.sub.sa.sub.s.sub.n, n. In one option, the basis set comprises a N.sub.3N.sub.3 DFT based matrix comprising basis vectors [a.sub.0, a.sub.1, . . . a.sub.N.sub.31] and the first basis set comprises a total of D basis vectors. For window n, the first basis set comprises the D.sub.n basis vectors given by

[00015]$\left(d_0,.Math.d_{D_n-1}\right)=\left(a_{\mathrm{mod}\left(a_{s_n}+0,N_3\right)},.Math.,a_{\mathrm{mod}\left(a_{s_n}+D_n-1,N_3\right)}\right).$

In one option, a.sub.s or a.sub.s.sub.n, n and/or N is configured to the UE.

Port Selection and Reporting

[0100] In accordance with embodiments, the UE is provided via a higher layer with a CSI report configuration by the network node, wherein the CSI report configuration indicates a higher layer parameter, P, indicating a number of antenna ports or CSI-RS ports.

[0101] In accordance with embodiments, the UE is configured to select a number of P.sub.l basis vectors from the second basis set, wherein the P.sub.l basis vectors are used to construct for each transmission layer the precoding vector or matrix, and to indicate the selected P basis vectors from the second basis set in the CSI report, or PMI as a part of the CSI report.

[0102] In one exemplary embodiment, the number of selected basis vectors, P.sub.l from the second basis set per transmission layer is identical for a subset of RI transmission layers, or all transmission layers l=0, . . . , RI1, wherein RI denotes the transmission rank of the precoding vector or matrix. In some examples, P.sub.l=P or P.sub.l=P/2 for a subset of RI transmission layers, or all transmission layers. In such a case, the precoding matrix is based on all P basis vectors from the second basis set for a subset of RI transmission layers, or all transmission layers. In some examples, P.sub.l<P for each transmission layer, a subset of RI transmission layers, or all transmission layers. In some examples, P.sub.lP or P.sub.l=P or P.sub.l P/2 or P.sub.l=P/2 for a first set of the RI transmission layers, and P.sub.l<P or P.sub.l<P/2 for a second set of the RI transmission layers. In one example, the first set of the RI transmission layers is {0,1} and the second set of the RI transmission layers is {2,3}. In another example, the first set of the RI transmission layers is {2,3} and the second set of the RI transmission layers is {0,1}.

[0103] In accordance with embodiments, the number of selected basis vectors, P.sub.l, from the second basis set per transmission layer satisfies a sum constraint across all RI transmission layers, wherein the total number of basis vectors selected from the second basis set across all layers is smaller than or equal to a value, R, with R being a positive integer. In one example, the sum constraint is defined by

[00016]${.Math.}_{l=0}^{\mathrm{RI}}{P}_l^{}{P}_0\mathrm{or}{.Math.}_{l=0}^{\mathrm{RI}}{P}_l^{}=P_0.$

Here, R=P.sub.0 denotes the maximum number of basis vectors selected by the UE across all layers. In one example, the value of R is configured to the UE. In another example, the value of R is fixed in the NR specification or derived by the UE based on the configured number of ports P or other configured parameters. In another example, the value of R is reported by the UE as a part of the CSI report.

[0104] In another example, the sum constraint is defined by

[00017]${.Math.}_{l=0}^{\mathrm{RI}}{P}_l^{}\mathrm{RI}.Math.P_0\mathrm{or}{.Math.}_{l=0}^{\mathrm{RI}}{P}_l^{}=\mathrm{RI}.Math.P_0\mathrm{or}$${.Math.}_{l=0}^{\mathrm{RI}}{P}_l^{}\mathrm{RI}.Math.P_0.$

Here, R=RI.Math.P.sub.0 denotes the maximum number basis vectors selected by the UE across all layers. The number of vectors P.sub.l per transmission layer may be selected by the UE. In addition,

[00018]$P_l^{}{\stackrel{}{P}}_l,$

where P.sub.l is the maximum number of basis vectors from the second basis set the UE can select for the l-th transmission layer. For example, the parameter P.sub.l may be identical across all layers, then P.sub.l=P. In one option, P=P.sub.0, wherein <1 or 1. The parameter P, , or the parameters P.sub.l may be configured to the UE, or is/are fixed in the NR specifications and known to the UE. In one option, the parameter P.sub.0 may be configured via a higher layer to the UE. In another option, the parameter P.sub.0 is fixed in the NR specifications and known by the UE. In another option, the UE selects and reports the parameter P.sub.0 (as a part of the CSI report).

[0105] In another example, for a given RI, the parameter P.sub.l may be identical for a subset of layers and different for different subsets. In one option, P.sub.l=.sub.0P.sub.0 for a first subset of layers (e.g., {0,1}) and P.sub.l=.sub.1P.sub.0 for the second subset of layers (e.g., {2,3}), where in .sub.0.sub.1, and wherein .sub.0<1 or .sub.01 and .sub.1<1 or .sub.11. The parameters P.sub.0, and/or .sub.0 and/or .sub.1 or the parameters P.sub.l may be configured to the UE, or is/are fixed in the NR specifications and known to the UE. In one example, only .sub.0 is configured and .sub.1 is derived from .sub.0 using a fixed rule. In one option, the parameter

[00019]$P_l^{}$

for each subset may be configured via a higher layer to the UE. In another option, the parameter P.sub.l for each subset is fixed in the NR specifications and known by the UE. In another option, the UE selects and reports the parameter P.sub.l for each subset (as a part of the CSI report).

[0106] In another example, the parameter P.sub.l may be different for different layers i.e.,

[00020]$P_l^{}=a_l{P}_0,$

wherein .sub.l1. The parameter P.sub.0, .sub.l, l>0 or the parameters P.sub.l may be configured to the UE, or is/are fixed in the NR specifications and known to the UE. In one option, only .sub.0 is configured and .sub.1,l>0 is derived from .sub.0 using a fixed rule. In another option, at is configured to the UE for each layer. In another option, the UE selects and reports the parameter P.sub.l for each layer (as a part of the CSI report).

[0107] In one example, P is dependent on the actual number of CSI-RS ports P. For PP.sub.t, P can be equal to P, whereas forP>P.sub.t, P=P.sub.0, wherein <1 or 1. In one option, P.sub.t{4,8,16,24}.

[0108] In one exemplary embodiment, the number of selected basis vectors,

[00021]$P_l^{}$

from the second basis set per transmission layer is identical for a subset of RI transmission layers or all transmission layers l=0, . . . , RI1. Then,

[00022]$P_l^{}=P^{}$

for the subset of RI transmission layers or all transmission layers.

[0109] In accordance with embodiments, the CSI report may comprise an RI, wherein the RI indicates the transmission rank (i.e., the number of transmission layers) of the precoding vector or matrix indicated by the CSI report, or the PMI as a part of the CSI report.

[0110] In accordance with embodiments, the CSI report, or the PMI as a part of the CSI report, may comprise a port indicator, PI, indicating the selected

[00023]$P_l^{}$

basis vectors from the second basis set of the precoding vector or matrix.

[0111] In some examples, the CSI report, or the PMI as a part of the CSI report, comprises a PI defined by a combinatorial bit indicator

[00024]$.Math.{\log }_2\left(\begin{array}{c}P\\ P_l^{}\end{array}\right).Math.\mathrm{or}.Math.{\log }_2\left(\begin{array}{c}P\\ P^{}\end{array}\right).Math.\mathrm{or}.Math.{\log }_2\left(\begin{array}{c}P/2\\ P_l^{}\end{array}\right).Math.\mathrm{or}.Math.{\log }_2\left(\begin{array}{c}P/2\\ P^{}\end{array}\right).Math.$

indicating the selected

[00025]$P_l^{}$

or P basis vectors from the second basis set.

[0112] In some examples, the CSI report, or the PMI as a part of the CSI report, comprises a port indicator wherein the PI includes a bit map of size P or P/2 for each transmission layer or all transmission layers of the precoding matrix indicating the selected

[00026]$P_l^{}$

or P basis vectors selected from the second basis set. Each bit in the bitmap may be associated with one basis vector of the second basis set. A 1 in the bitmap may indicate that the associated basis vector is selected, and 0 in the bitmap may indicate that the associated basis vector is not selected for the precoding vector or matrix.

[0113] In one instance, the selected

[00027]$P_l^{}$

or P basis vectors selected from the second basis set are identical for a subset of the RI transmission layers or all RI transmission layers, and the CSI report, or the PMI as a part of the CSI report, comprises only a single PI for a subset of the RI transmission layers, or for all RI transmission layers.

[0114] In the following embodiments, different reporting schemes for the port indication that reduce the feedback overhead of the CSI report are presented.

In accordance with embodiments, the UE is configured to determine a common basis set comprising at least the selected basis vectors from the second basis set across a subset of the RI transmission layers or across all RI transmission layers, and to indicate the basis vectors of the common basis set in the CSI report. The indicator for the basis vectors of the common basis set is referred to as common basis set indicator (CBSI) in the following. The CSI report, or the PMI as a part of the CSI report, may include the CBSI. Moreover, the UE is configured to indicate the basis vectors selected from the common basis set for each transmission layer of the precoding vector or matrix by a layer-specific basis set indicator, LBSI, in the CSI report.

[0115] In some examples, the CBSI is given by a combinatorial bit indicator

[00028]$.Math.{\log }_2\left(\begin{array}{c}P\\ P^{}\end{array}\right).Math.\mathrm{or}.Math.{\log }_2\left(\begin{array}{c}P/2\\ P^{}\end{array}\right).Math.$

indicating P selected vectors from the second basis set across a subset of the RI transmission layers or across all RI transmission layers of the precoding vector or matrix. The parameter P may be either configured to the UE, reported by the UE, or it is fixed in the NR specifications and known by the UE. In some examples, the CBSI is given by a bit map of size P or P/2 indicating P basis vectors selected from the second basis set across a subset of the RI transmission layers or across all RI transmission layers of the precoding matrix. A 1 in the bitmap may indicate that the associated vector is selected for the precoding matrix, and 0 in the bitmap may indicate that the associated vector is not selected for the precoding matrix.

[0116] In some examples, the CBSI can be represented by a continuous set A comprising P entries, wherein each entry/value of set A is associated with one basis vector of the second basis set. In one example, the continuous set A is represented by A={P.sub.S, P.sub.S+1, . . . , P.sub.S+P1}. In another example, continuous set A is represented by A={P.sub.SmodP.sub.A, (P.sub.S+1)mod P.sub.A, . . . , (P.sub.S+P1)mod P.sub.A} wherein P.sub.A=P or P.sub.A=P/2. Here, a mod b denotes the modulo operator of a modulo b. The CBSI indicates P basis vectors from the second basis set.

[0117] In accordance with embodiments, the parameter P may be configured to the UE, or indicated by the UE in the CSI report, or known by the UE and fixed in the NR specification. The parameter P may also be given by a combination of other parameters which are configured to the UE, or known by the UE and fixed in the NR specification.

[0118] In accordance with embodiments, the parameter P.sub.S may be configured to the UE, or indicated by the UE in the CSI report, or known by the UE and fixed in the NR specification. The parameter P.sub.S may also be given by a combination of other parameters which are configured to the UE, or known by the UE and fixed in the NR specification.

[0119] In some examples, the LBSI is defined for each transmission layer or by a P-sized bitmap, and each bit in the bitmap is associated with one entry of the CBSI.

[0120] To indicate the basis vectors selected from the common basis set for each transmission layer of the precoding vector or matrix by a layer-specific basis set indicator, LBSI, is included in the CSI report.

[0121] The bitmap for the I-th layer may comprise

[00029]$P_l^{}$

1s or less than

[00030]$P_l^{}$

1s. A 1 in the bitmap may indicate that the associated port, or port index of the CPI, and hence the associated PS vector from the set of P.sub.A PS basis vectors, is selected for the precoding matrix for the I-th transmission layer. When the CPI is represented by set A, each bit in the bitmap is associated with one entry of set A.

[0122] In some examples, the layer-specific port indicator, LSPI, is defined by a combinatorial bit indicator

[00031]$.Math.{\log }_2\left(\begin{array}{c}{P}^{}\\ {P_l}^{}\end{array}\right).Math.$

indicating

[00032]${P_l}^{}$

entries of the CBSI, and hence

[00033]${P_l}^{}$

PS vectors selected from the set of P.sub.A PS basis vectors, for the I-th transmission layer of the precoding matrix.

[0123] In accordance with embodiments, the UE is configured to group the basis vectors of the second basis set into B basis subsets, wherein each basis subset comprises a number of basis vectors. In one option, B is equal to P. In another option, B is less than. The number of basis vectors per basis subset may be given by

[00034]$E=\frac{P}{B},$

wherein each basis subset comprises E basis vectors, and wherein the parameter E or the parameter B can be configured to the UE, or it is fixed in the NR specifications, or it is determined by the UE based on the number of configured ports, P, or it is reported by the UE.

[0124] In accordance with embodiments, the basis vectors of the second basis set are grouped into B basis subsets, wherein each basis subset comprises a number of basis vectors, and the UE is configured to select b.sub.l basis subsets out of the B basis subsets per layer for the precoding vector or matrix and to indicate the selected b.sub.l basis subsets in the CSI report, wherein b.sub.l>0.

[0125] In accordance with embodiments, the UE is configured to select b.sub.l basis subsets out of B basis subsets for each layer of the precoding vector or matrix and to indicate the selected b.sub.l basis subsets in the CSI report. In one example, the b.sub.l basis subsets are indicated per layer, subsets of layers, or all layers in the CSI report by a B-sized bitmap, where the b-th bit in the bitmap is associated with the b-th basis subset, and the bitmap contains b.sub.l1s per layer. In another example, the b.sub.l basis subsets are indicated per layer, subsets of layers, or all layers in the CSI report by a combinatorial bit indicator

[00035]$.Math.{\log }_2\left(\begin{array}{c}B\\ b_l\end{array}\right).Math..$

The number of selected basis subsets (b.sub.l) may be fixed, configured to the UE or reported to the gNB by the UE. When the selected basis subsets b.sub.l are identical for a subset of layers or all layers, a single indicator for each layer subset or all layers is used in the CSI report. In one example, the selected basis subsets b.sub.l is identical for all layers, a subset of layers or different for all layers. In another example, the number of selected basis subsets b.sub.l may be identical for all layers, a subset of layers or different for all layers.

[0126] In accordance with embodiments, the UE is configured to select a number of basis vectors within each selected basis subset per layer or subset of layers or all layers and indicate the selected basis vectors in the CSI report.

[0127] In one example, the selected basis vectors from b.sub.l basis subsets per layer are indicated in the CSI report by a b.sub.lE-sized bitmap. In another example, the selected basis vectors from b.sub.l basis subsets per layer are indicated in the CSI report by a combinatorial bit indicator

[00036]$.Math.{\log }_2\left(\begin{array}{c}{b}_{l}E\\ P_l^{}\end{array}\right).Math.,$

where

[00037]$P_l^{}$

basis vectors are selected from b.sub.lE basis vectors per layer. In another example, the selected basis vectors from b.sub.l basis subsets for a subset of layers or all layers may be indicated using a combinatorial

[00038]$.Math.{\log }_2\left(\begin{array}{c}{b}^{}E\\ P_0\end{array}\right).Math.,$

where

[00039]$b^{}={.Math.}_l{b}_l^{}\mathrm{and}{P}_0={.Math.}_l{P}_l^{}.$

In one option, the values of P.sub.0 and/or

[00040]$P_l^{}$

are indicated by the UE in the CSI report. In another option, the values of P.sub.0 and/or

[00041]$P_l^{}$

are fixed in the NR specification. In another option, the values of P.sub.0 and/or

[00042]$P_l^{}$

are configured to the UE. When the selected vectors are identical for a subset of layers or all layers, a single indicator for each layer subset or all layers is used in the CSI report.

[0128] In accordance with embodiments, the basis vectors of the second basis set are grouped into B basis subsets, wherein each basis subset comprises a number of basis vectors, and the UE is configured to select b.sub.l basis subsets out of the B basis subsets for each layer for the precoding vector or matrix and to indicate the selected b.sub.l basis subsets in the CSI report using a first indicator. From the selected basis subsets, the UE is configured to select a number of basis vectors within each selected basis subset per layer or subset of layers or all layers and indicate the selected basis vectors in the CSI report using a second indicator. In one option, the first indicator is given by a bitmap of size B bits, whereas the second indicator is given by a bitmap of size b.sub.lE bits. In another option, the first indicator is given by a bitmap of size B bits, whereas the second indicator is given by a combinatorial indicator of size

[00043]$.Math.{\log }_2\left(\begin{array}{c}{b}_{l}E\\ P_l^{}\end{array}\right).Math..$

In another option, the first indicator is given by a combinatorial indicator of size

[00044]$.Math.{\log }_2\left(\begin{array}{c}B\\ b_l\end{array}\right).Math.,$

whereas the second indicator is given by a bitmap of size b.sub.lE bits. In another option, the first indicator is given by a combinatorial indicator of size

[00045]$.Math.{\log }_2\left(\begin{array}{c}B\\ b_l\end{array}\right).Math.,$

whereas the second indicator is given by a combinatorial indicator of size

[00046]$.Math.{\log }_2\left(\begin{array}{c}{b}_{l}E\\ P_l^{}\end{array}\right).Math..$

[0129] In one example, the first indicator may be layer common and the second indicator may be layer specific. In another example, the first indicator may be layer common and the second indicator may also be layer specific. In another example, the first indicator may be layer common and the second indicator may be common for a subset of layers and different for different subsets of layers. In one example, the first indicator may be layer specific and the second indicator may be layer specific. In another example, the first indicator may be layer specific and the second indicator may also be layer common. In another example, the first indicator may be common for a subset of layers and different for different subsets of layers and the second indicator may be common for a subset of layers and different for different subsets of layers. In another example, the first indicator may be common for a subset of layers and different for different subsets of layers and the second indicator may be common for all layers. In another example, the first indicator may be common for a subset of layers and different for different subsets of layers and the second indicator may be layer specific. When an indicator (either first or second) is layer common, only one indicator for all RI layers is included in the CSI report. When an indicator (either first or second) is layer specific, one indicator for each layer is included in the CSI report. When an indicator (either first or second) is common for a subset of layers and different for different subsets of layers, then one indicator for each subset of layers in included in the CSI report.

Indication of Combining Coefficients in the CSI Report

[0130] In accordance with embodiments, the UE is configured to select a number of combining coefficients per layer used to combine the one or more vectors selected from the first and second basis sets and to indicate the selected combining coefficients in the CSI report.

[0131] In accordance with embodiments, the UE is configured with a maximum number, K.sub.0, combining coefficients per layer of the precoding vector or matrix, and to select K.sub.1 combining coefficients per layer and to indicate the selected K.sub.1 combining coefficients in the CSI report, wherein K.sub.1K.sub.0.

[0132] In accordance with embodiments, the UE is configured with a maximum number, K.sub.0, combining coefficients per subset of layers or all layers, and to select K.sub.1 combining coefficients per subset of layers or all layers, and to indicate the selected K.sub.1 combining coefficients in the CSI report, wherein K.sub.1K.sub.0.

[0133] In accordance with embodiments, K.sub.1K.sub.0 and K.sub.1K.sub.0.

[0134] In accordance with embodiments, K.sub.0=2K.sub.0.

[0135] In accordance with embodiments, the maximum number, K.sub.0, or K.sub.0 of combining coefficients per layer, or subset of layers, or all layers of the precoding vector or matrix contained in a CSI report is defined by K.sub.0=P, or K.sub.0=P, K.sub.0=P, or K.sub.0=P, wherein <1, <1 or {0.5,0.75, 1,1.25,1.5,2} or {0.5,0.75, 1,1.25,1.5,2}.

[0136] In accordance with embodiments, K.sub.0 is smaller than a total of T coefficients.

[0137] In accordance with embodiments, the CSI report comprises K.sub.1 combining coefficients out of a total of T coefficients per layer, subset of layers, or all layers, wherein K.sub.1<T or K.sub.1T.

[0138] In accordance with embodiments, the CSI report comprises an indication on the number of combining coefficients K.sub.1 per layer, and/or across subset of layers, and/or across all layers.

[0139] In accordance with embodiments, the number of combining coefficients K.sub.1 per layer, and/or across subset of layers, and/or across all layers is selected by the UE and indicated in the CSI report.

[0140] In accordance with embodiments, the number of combining coefficients K.sub.1 per layer, and/or across subset of layers, and/or across all layers is configured to the UE, e.g., via a higher layer from a network node, or it is fixed in the NR specifications.

[0141] The parameter K.sub.1 may be defined by a combination of parameters (e.g., T, K.sub.0, and/or the RI value) or may depend on the number of CSI-RS ports, P, configured to the UE. For example, the number of non-zero coefficients per layer, subset of layers, or across all layers K.sub.1=P, where

[00047]$<1\mathrm{or}\left\{\frac{1}{2},\frac{3}{4},1,\frac{5}{4},\frac{3}{2},2\right\}.$

In another example, the parameter K.sub.1 may depend on the total number of selected CSI-RS ports across all layers

[00048]$\left(P_l^{}\right).$

In another example, the parameter K.sub.1 may depend on the maximum number of selected CSI-RS ports across all layers (P.sub.m), where

[00049]$P_m=\max \left(P_l^{}\right),l.$

[0142] In one exemplary embodiment, parameter K.sub.1 indicating the number of coefficients reported by the UE per layer, or a subset of layers, or for all layers is RI-common. This means, the parameter K.sub.1 does not depend on the RI value of the precoding vector or matrix.

[0143] In one exemplary embodiment, the parameter K.sub.1 indicating the number of coefficients reported by the UE per layer, or a subset of layers, or for all layers is RI-specific. This means, the parameter K.sub.1 may depend on the RI value of the precoding vector or matrix. For example, for RI=1, the parameter K.sub.1 is given by K.sub.1=[P.sub.e], where <1 or 1 and for RI>1, the parameter K.sub.1 is given by K.sub.1=2[P.sub.e], where <1 or 1 and

[00050]$P_e=P\mathrm{or}{P}_e=P_l^{}\mathrm{or}{P}_e=P_m.$

[0144] In one exemplary embodiment, the CSI report comprises K.sub.1 combining coefficients per layer, subset of layers, or all layers, selected from K.sub.0 or 2K.sub.0 combining coefficients, wherein K.sub.1 is either freely selected by the UE, wherein K.sub.1K.sub.0 and K.sub.0 is smaller than a total of T coefficients or K.sub.1 is configured to the UE.

[0145] In accordance with embodiments, the CSI report comprises a coefficient indicator indicating the selected combining coefficients out of a total of T coefficients per transmission layer of the precoding vector matrix.

[0146] In one exemplary embodiment, the coefficient indicator is a bitmap of size T wherein each bit in the bitmap is associated with a coefficient. When a bit in the bitmap is set to 1 the associated coefficient is contained in the CSI report and a bit in the bitmap is set to 0 the associated coefficient is not contained in the CSI report.

[0147] In one exemplary embodiment, the coefficient indicator is a bitmap of size T wherein each bit in the bitmap is associated with a selected basis vector from the first basis set and a basis vector from the second basis set. When a bit in the bitmap is set to 1 the associated coefficient is contained in the CSI report and a bit in the bitmap is set to 0 the associated coefficient is not contained in the CSI report.

[0148] In one exemplary embodiment, the coefficient indicator is a combinatorial bit indicator

[00051]$.Math.{\log }_2\left(\begin{array}{c}T\\ K_1\end{array}\right).Math.$

indicating the selected K.sub.1 combining coefficients out of a total of T combining coefficients.

[0149] In accordance with embodiments, T=PD, T=PD, T=2PD,

[00052]$T=P_l^{}D$

or T=P.sub.mD per layer, or T=RI.Math.PD, T=RI.Math.PD, T=P.sub.0D, T=RI.Math.P.sub.tD, T=RI.Math.P.sub.mD or T=RI.Math.2PD per layer or for all layers or for a subset of layers.

[0150] In accordance with embodiments, when D=1, the coefficient selection indication (e.g., via a bitmap or a combinatorial indicator) is not included in the CSI report, whereas forD>1, the coefficient selection indication (e.g., via a bitmap or a combinatorial indicator) is included in the CSI report.

UCI Reporting

[0151] In accordance with embodiments, the UE is configured to feedback the CSI report as a part of the uplink control information (UCI) over an uplink channel, where an uplink channel can be the PUCCH, or der the PUSCH, or a combination thereof.

[0152] In accordance with embodiments, the CSI report comprises at least two parts, CSI part 1 and CSI part 2, wherein the first part, CSI part 1, has a fixed payload size and indicates the size of second part, CSI part 2.

[0153] In accordance with embodiments, the CSI part 1 comprises an indication of the total number of selected basis vectors (or port indices) from the second basis set per layer, subset of layers, or across all layers of the precoding vector or matrix.

[0154] In accordance with embodiments, the CSI part 1 comprises an indication of the maximum number of selected basis vectors (port indices) (P.sub.m) from the second basis set across a subset of layers or across all layers of the precoding vector or matrix.

[0155] In order to perform the previously described process or method steps related to the radio network node (e.g. a radio base station or gNB), some embodiments herein include a network node for receiving feedback from a UE as previously described. As shown in FIG. 4, the network node or radio base station or gNB 800 comprises a processor 810 or processing circuit or a processing module or a processor or means 810; a receiver circuit or receiver module 840; a transmitter circuit or transmitter module 850; a memory module 820 a transceiver circuit or transceiver module 830 which may include the transmitter circuit 850 and the receiver circuit 840. The network node 800 further comprises an antenna system 860 which includes antenna circuitry for transmitting and receiving signals to/from at least the UE. The antenna system employs beamforming as previously described.

[0156] The network node 500 may belong to any radio access technology including 2G, 3G, 4G or LTE, LTE-A, 5G, WLAN, and WiMax etc. that support beamforming technology.

[0157] The processing module/circuit 810 includes a processor, microprocessor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA), or the like, and may be referred to as the processor 810. The processor 810 controls the operation of the network node 800 and its components. Memory (circuit or module) 820 includes a random access memory (RAM), a read only memory (ROM), and/or another type of memory to store data and instructions that may be used by processor 810. In general, it will be understood that the network node 800 in one or more embodiments includes fixed or programmed circuitry that is configured to carry out the operations in any of the embodiments disclosed herein.

[0158] In at least one such example, the network node 800 includes a microprocessor, microcontroller, DSP, ASIC, FPGA, or other processing circuitry that is configured to execute computer program instructions from a computer program stored in a non-transitory computer-readable medium that is in, or is accessible to the processing circuitry. Here, non-transitory does not necessarily mean permanent or unchanging storage, and may include storage in working or volatile memory, but the term does connote storage of at least some persistence.

[0159] The execution of the program instructions specially adapts or configures the processing circuitry to carry out the operations disclosed herein including anyone of method steps already described. Further, it will be appreciated that the network node 800 may comprise additional components not shown in FIG. 4.

[0160] Details on the functions and operations performed by the network node have already been described and need not be repeated again.

[0161] In order to perform the previously described process or method steps related to the UE or communication device or radio device, some embodiments herein include a UE for providing efficient feedback reporting for at least a New Radio-(NR) based wireless communication network system, which feedback includes Channel State Information (CSI).

[0162] As shown in FIG. 5, the UE 900 comprises a processor 910 or processing circuit or a processing module or a processor or means 910; a receiver circuit or receiver module 940; a transmitter circuit or transmitter module 950; a memory module 920 a transceiver circuit or transceiver module 930 which may include the transmitter circuit 950 and the receiver circuit 940. The UE 900 further comprises an antenna system 960 which includes antenna circuitry for transmitting and receiving signals to/from at least the UE. The antenna system employs beamforming as previously described.

[0163] The network node 500 may belong to any radio access technology including 2G, 3G, 4G or LTE, LTE-A, 5G, WLAN, and WiMax etc. that support beamforming technology.

[0164] The processing module/circuit 910 includes a processor, microprocessor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA), or the like, and may be referred to as the processor 910. The processor 910 controls the operation of the network node 900 and its components. Memory (circuit or module) 920 includes a random access memory (RAM), a read only memory (ROM), and/or another type of memory to store data and instructions that may be used by processor 910. In general, it will be understood that the UE 900 in one or more embodiments includes fixed or programmed circuitry that is configured to carry out the operations in any of the embodiments disclosed herein.

[0165] In at least one such example, the UE 900 includes a microprocessor, microcontroller, DSP, ASIC, FPGA, or other processing circuitry that is configured to execute computer program instructions from a computer program stored in a non-transitory computer-readable medium that is in, or is accessible to the processing circuitry. Here, non-transitory does not necessarily mean permanent or unchanging storage, and may include storage in working or volatile memory, but the term does connote storage of at least some persistence. The execution of the program instructions specially adapts or configures the processing circuitry to carry out the operations disclosed herein including anyone of method steps already described. Further, it will be appreciated that the UE 900 may comprise additional components not shown in FIG. 5.

[0166] Details on the functions and operations performed by the UE have already been described and need not be repeated.

[0167] It will be understood that the invention is not restricted to the aforedescribed and illustrated exemplifying embodiments thereof and that modifications can be made within the scope of the inventive concept as defined by the accompanying Claims.