This application provides a communication method, to provide a codebook of a higher-order precoding matrix, and help increase a quantity of layers of data, thereby helping improve a data transmission capability and improving a throughput. The method includes: receiving, by a first device, a reference signal used for channel measurement; and sending, by the first device, at least one precoding matrix indicator PMI and a rank indication RI based on the reference signal, where the PMI is used to indicate a precoding matrix in a codebook corresponding to the RI, the precoding matrix in the codebook includes a plurality of matrices in a one-to-one correspondence with a plurality of antenna port groups, a matrix corresponding to one antenna port group or each of at least two antenna port groups has two different inter-antenna-port-group phase factors, and any two column vectors in the precoding matrix are orthogonal to each other.

A wireless communication device including a control unit configured to generate information for a terminal device based on information acquired from the terminal device. The control unit outputs a reference signal on a first beam generated with at least two or more different first weighting matrices, generates a second weighting matrix specific to a terminal device in accordance with information transmitted from the terminal device in accordance with the reference signal, and outputs data for the terminal device on a second beam with the first weighting matrices and the second weighting matrix. The wireless communication device can supply an appropriate beam to a terminal device while preventing a problem with overhead or increase in the cost of a wireless device, which are caused by an increasing number of antenna elements when FD-MIMO is used.

Example embodiments are presented for codebook subset restriction and precoder selection in wireless communications systems. For instance, an example method for codebook subset restriction at a user equipment (UE) is presented. In the example method, the UE can receive, from a network node such as a gNB, codebook subset restriction (CBSR) signaling for a first component common to precoders in a first group of codebooks. In an aspect of the present disclosure, a restriction of the first component maps to a restriction of a second component and the second component is common to precoders in a second group of codebooks. In addition, the example method includes restricting precoders selectable from a codebook in the second group of codebooks based on the second component. Network-side methods are presented, as well as example UEs and network nodes.

A channel state information reporting method and apparatus are described. The method can include a terminal device obtaining first indication information and sending the first indication information to a network device. The network device receives the first indication information, where the first indication information indicates a differential value between channel state information of a first antenna port set and channel state information of a second antenna port set. The first antenna port set includes x antenna ports of the terminal device, the second antenna port set includes m antenna ports of the terminal device, and the first antenna port set is different from the second antenna port set. The channel state information reporting method and apparatus in embodiments of this application help improve accuracy of channel state information obtained by a network device, and improve data transmission performance.

A communication device for providing an explicit channel state information, CSI, feedback in a wireless communication system includes a transceiver to receive, from a transmitter a radio signal via a radio time-variant frequency MIMO channel, the radio signal including downlink reference signals according to a reference signal configuration, and downlink signals including the reference signal configuration, and a processor. The processor estimates the CSI using measurements on the downlink reference signals of the radio channel according to the reference signal configuration over one or more time instants/slots, constructs a frequency-domain channel tensor using the CSI estimate, performs a higher-order principal component analysis, HO-PCA, on the channel tensor, identifies a plurality of dominant principal components of the channel tensor, thereby obtaining a compressed channel tensor, and reports to the transmitter the explicit CSI including the dominant principal components of the channel tensor.

To provide a base station apparatus, a terminal apparatus and a communication method which enable improvements in throughput and communication quality while suppressing an increase in complexity even in a case that the accuracy of a CSI report is improved. A terminal apparatus is provide with: a receiver configured to receive a CSI-RS and configuration information of a CSI report; and a transmitter configured to transmit CSI relating to the CSI-RS, wherein the CSI includes a first PMI and a second PMI, the first PMI is an indicator indicating multiple vectors, the second PMI includes either or both of a first indicator and a second indicator, the first indicator is an indicator indicating one or more complex weights of a first dimension for the multiple vectors, the second indicator is an indicator indicating one or more complex weights of a second dimension for the multiple vectors, and configuration information of the CSI report includes information indicating whether or not the second PMI includes the first indicator.

Embodiments of this application disclose a precoding matrix determining method and apparatus, to determine a stage-1 precoding matrix based on indication information that is of a spatial correlation matrix and that is fed back by a terminal, thereby implementing three-dimensional precoding based on a channel state and increasing a channel capacity. The method includes: sending, by a base station, a plurality of groups of first reference signals, where the plurality of groups of first reference signals are in a one-to-one correspondence with a plurality of dimensions of an antenna array, and each of the plurality of groups of first reference signals is used by a terminal to estimate spatial correlation matrix information in a corresponding dimension; receiving the spatial correlation matrix information fed back by the terminal based on the plurality of groups of first reference signals; and determining a stage-1 precoding matrix based on the spatial correlation matrix information.

The present invention relates to a multi-input and multi-output communication method in a large-scale antenna system. An MIMO transmission method according to the present invention includes: obtaining statistical channel information on at least one terminal, dividing terminals into a plurality of classes and a plurality of groups based on the statistical channel information, wherein the groups depend on the classes; determining a group beam-forming matrix for each of the divided groups; performing a group beamforming transmission by group based on the group beam-forming matrix to obtain instantaneous channel information; and scheduling terminals based on the instantaneous channel information. Thus, it is possible to decrease the complexity in a scheduling and precoding calculation without an increase in the amount of wireless resources that are required for providing feedback for a reference signal and channel status information.

A method and apparatus is disclosed herein for wireless transceiver calibration. In one embodiment, the method for relative calibration of multiple transceiver units for their use for joint transmission from groups of transceiver units to at least one other wireless entity, wherein each transceiver unit includes an antenna element, comprises: exchanging pilots using multiple signaling resource slots, using at least two non-overlapping groups of transceiver units; and performing calibration of transceiver units in the first and second groups of transceiver units, including choosing relative calibration parameters to control calibration and using a metric to assess calibration, where the metric is based on at least one combination of calibration parameters and the observations of each transceiver group in at least two groups of transceiver units based the simultaneous pilot broadcast and subsequent reception between transceiver units in pairs of groups of transceiver units.

For CSI reporting mechanisms, a user equipment (UE) includes a transceiver and a processor operably connected to the transceiver. The transceiver is configured to receive channel state information (CSI) process configuration information including at least one beamformed type associated with a plurality of non-zero-power (NZP) CSI reference signal (CSI-RS) resource configurations and receive a CSI-RS resource index (CRI) reporting configuration. The processor is configured to calculate, in response to receipt of the configuration information, a CRI and a channel quality indicator (CQI). The transceiver is further configured to report the CRI and the CQI by transmitting the CRI and the CQI on an uplink channel.