This communication device comprises: a control circuit that, on the basis of first information relating to the reception quality of a plurality of spatial streams, determines a spatial stream for feeding back second information; and a transmission circuit that transmits the second information relating to the determined spatial stream.

In accordance with an example embodiment of the present invention, a method comprising: selecting, by a user equipment, a subset of linear combination coefficients from a linearized two-dimensional matrix having columns of frequency domain components and rows of spatial beams components for channel state information determination, wherein the number of linear combination coefficients in the subset is less than all of the linear combination coefficients; determining indication comprising information associated with column indices of the selected subset of linear combination coefficients from the linearized two-dimensional matrix, wherein the indication excludes the index of the column with lowest index of the linearized two-dimensional matrix; determining compressed channel state information comprising locations in the linearized two-dimensional matrix of the subset of linear combination coefficients and corresponding values of the linear combination coefficients at those locations; and reporting, from the user equipment toward the base station, the compressed channel state information.

This disclosure relates to channel state information reference signal configuration, precoding, and transmission, and channel state information feedback configuration, compression, and transmission in multiple-input and multiple-output (NEMO) wireless communication systems. The various embodiments provide channel state information reference signal and feedback schemes which facilitate a decrease of the amount of information that need to be transmitted and reduce communication resource overhead for channel state information configuration and feedback.

This disclosure relates to channel state information reference signal configuration, precoding, and transmission, and channel state information feedback configuration and transmission in multiple-input and multiple-output (MIMO) wireless communication systems. The various embodiments provide channel state information reference signal and feedback schemes which facilitate a decrease of the amount of information that need to be transmitted and reduce communication resource overhead for channel state information configuration and feedback.

This application provides channel state information reporting methods and communications apparatuses. One method includes: generating first indication information and a plurality of groups of second indication information, where the first indication information indicates a plurality of frequency domain component vectors, each group in the plurality of groups of second indication information corresponds to a spatial layer and a plurality of spatial domain component vectors and constructs precoding vectors of the spatial layer in a plurality of frequency bands, and each piece of second indication information in each group corresponds to a spatial domain component vector in the plurality of spatial domain component vectors and indicates at least one of the plurality of frequency domain component vectors that corresponds to the spatial domain component vector; and sending the first indication information and the second indication information.

A method for operating a user equipment (UE) comprises receiving configuration information about a channel state information (CSI) report, the configuration information including codebook parameters (M, α, β), wherein: M is a number of frequency domain basis vectors, α is a number ≤1, and β is a number ≤1; identifying values of M, α, and β; determining a value of K.sub.1 based on α, where K.sub.1 is a number of selected CSI reference signal (CSI-RS) ports from a total of P CSI-RS ports; determining a maximum number of non-zero coefficients based on β; determining the CSI report based on the values of M, K.sub.1, and the maximum number of non-zero coefficients; and transmitting the CSI report.

The present disclosure relates to methods and apparatuses (UE, network node or gNB) for CSI reporting. The method performed by a UE comprises: receiving from the gNB, a radio signal via a MIMO channel, wherein the radio signal contains at least one DL-RS according to a DL-RS configuration; estimating said MIMO channel based on said received at least one DL reference signal for configured subbands; calculating a precoder matrix or a CSI matrix for a number of antenna ports of the gNB and configured subbands; the precoder matrix based on a first codebook and on a second codebook and a set of combining coefficients for complex scaling/combining one or more of vectors selected from the first codebook and the second codebook; and reporting, to the gNB, a CSI feedback report and/or a PMI/RI, used to indicate the precoder matrix or the CSI matrix for the configured antenna ports and subbands.

The present disclosure relates to methods and apparatuses (UE, network node or gNB) for CSI reporting. The method performed by a UE comprises: receiving from the gNB, a radio signal via a MIMO channel, wherein the radio signal contains at least one DL-RS according to a DL-RS configuration; estimating said MIMO channel based on said received at least one DL reference signal for configured subbands; calculating a precoder matrix or a CSI matrix for a number of antenna ports of the gNB and configured subbands; the precoder matrix bcing based on a first codebook and on a second codebook and a set of combining coefficients for complex scaling/combining one or more of vectors selected from the first codebook and the second codebook; and reporting to the gNB, a CSI feedback report and/or a PMI/RI, used to indicate the precoder matrix or the CSI matrix for the configured antenna ports and subbands.

The generation of a channel state information report is provided. The generation includes transmitting reference signals to a user equipment, and receiving a reported set of quantized weighting coefficients, each of the weighting coefficients corresponding to a respective beam index and a respective tap index, where a set of beams based on the received reference signals is selected, where each of the beams corresponds to a discrete Fourier transform vector, and where each of the beams has a corresponding beam index. The tap index corresponds to a member of a Fourier basis set, where at least two subsets of the reported set of weighting coefficients are quantized according to separate quantization procedures.

A method (1400) performed by a wireless device (200) for multibeam precoder based channel state information, CSI, feedback reporting is provided, A CSI report comprises a first part, CSI Part 1, and a second part, CSI Part 2. The method (1400) comprises generating (1401) the CSI report, wherein the CSI Part 1 comprises an indication of a number of non-zero coefficients, and a payload size of the indication of the number of non-zero coefficients is dependent on a rank restriction of the wireless device. The method also comprising transmitting (1402) the CSI report to a network node, wherein one or more of a payload of the CSI Part 2 and payload size of the CSI Part 2 is based on the number of non-zero coefficients indicated in the CSI Part 1.