Methods, systems, and devices for wireless communications are described. A user equipment (UE) may determine that a base station has scheduled the UE for one or more downlink transmissions, each of the one or more downlink transmissions having an associated repetition factor that corresponds to one of a plurality of configured repetition factors configured at the UE. The UE may identify an applied repetition factor to apply to feedback codebook generation for the one or more downlink transmissions. The UE may generate a feedback codebook for reporting feedback for the one or more downlink transmissions, the feedback codebook populated based at least in part on the applied repetition factor and on whether the one or more downlink transmissions were successfully received and decoded. The UE may transmit to the base station a feedback report that includes the feedback codebook.

A UE determines a PMI, by performing at least the following: determining an intermediate set of vectors from a FD codebook; forming a subset of the intermediate set of vectors; mapping the subset of vectors to a combinatorial indicator; and forming the PMI at least from the combinatorial indicator. The UE sends the PMI toward a wireless network. A base station receives the PMI from the UE. The PMI includes a combinatorial indicator that maps to a subset of vectors from the FD codebook. The base station determines, using at least the received PMI, information from at least the FD codebook to apply to data for transmission toward the UE.

The teachings herein present a method and apparatus that implement and use a factorized precoder structure that is advantageous in terms of performance and efficiency. In particular, the teachings presented herein disclose an underlying precoder structure that allows for certain codebook reuse across different transmission scenarios, including for transmission from a single Uniform Linear Array (ULA) of transmit antennas and transmission from cross-polarized subgroups of such antennas. According to this structure, an overall precoder is constructed from a conversion precoder and a tuning precoder. The conversion precoder includes antenna-subgroup precoders of size N.sub.T/2, where N.sub.T represents the number of overall antenna ports considered. Correspondingly, the tuning precoder controls the offset of beam phases between the antenna-subgroup precoders, allowing the conversion precoder to be used with cross-polarized arrays of N.sub.T/2 antenna elements and with co-polarized arrays of N.sub.T antenna elements.

A method, wireless device and network node for determining an indication of a precoder are provided. According to one aspect, a method in a wireless device includes determining and the indication of the precoder from a codebook, the indication comprising a first beam phase parameter and a second beam phase parameter corresponding to a first beam and a second beam respectively. The first beam phase parameter takes on one of a first integer number of phase values and the second beam phase parameter takes on one of a second integer number of phase values. At least one of the following conditions apply: the second integer number of phase values is less than the first number of phase values, and the second frequency-granularity is greater than the first frequency-granularity. The method includes transmitting the determined indication of a precoder to the network node.

Precoding matrix indicator (PMI) feedback for Type II channel state information (CSI) feedback in new radio (NR) multiple input, multiple output (MIMO) operations is discussed. According to various aspects, a user equipment (UE) determines a plurality of CSI feedback components and identifies a set of discarded ones of these components based on a particular component value of a precoding matrix indicator (PMI) component. The UE may then generate an adjusted CSI report by adjusting how the discarded feedback components are treated. The resulting adjusted CSI report may then be transmitted to a serving base station.

Apparatuses, methods, and systems are disclosed for preparing CSI. One apparatus includes a processor and a memory with instructions executable by the processor to cause the apparatus to determine a total number of non-zero coefficients associated with a CSI codebook over a set of transmission layers and encode an indication of the total number of non-zero coefficients by selecting a codeword from a plurality of candidate codewords in which the selected codeword identifies the total number of non-zero coefficients. The instructions are executable by the processor to prepare CSI based on the CSI codebook and to transmit the CSI to a base station unit, where the CSI codebook includes a plurality of precoding matrices, and where the CSI includes the selected codeword.

A codebook feedback method includes a network device sending a first indication information to a terminal device, wherein the first indication information is used to indicate at least one set of basis vector sets, and the at least one set of basis vector sets includes a frequency domain basis (FD basis) set or a spatial domain-frequency domain-basis (SD-FD-basis) set.

Embodiments of this application provide an update method and a communications apparatus. The method includes: generating space domain vector update information, where the space domain vector update information is for updating a first group of space domain vectors to obtain a second group of space domain vectors, the space domain vector update information includes a plurality of groups of space domain vector coefficients, and each group of space domain vector coefficients is for performing weighted combination on the first group of space domain vectors, to obtain one space domain vector in the second group of space domain vectors; and sending the space domain vector update information.

A base station may transmit to a device an indication of codebook subset restriction (CBSR), which includes at least a restriction on a frequency basis. The device may receive the indication of CBSR, and may transmit to the base station channel state information (CSI) according to the received indication of CBSR. The indication of CBSR may also include a restriction on a spatial basis and restrict the device from reporting the CSI based on a subset of the frequency basis in addition to the spatial basis per configuration of the base station. The indication of CBSR may include a separately configured maximum allowed amplitude of a weighting coefficient for the spatial basis and the frequency basis, where the weighting coefficient is associated with a column vector of a precoding matrix used by the base station and the device. The number of frequency bases and the frequency compression units may be determined based on a number of different criteria, for example the number of antennas, the number of subbands, etc.

Apparatuses and methods for multi-stage UL precoding are provided. The method includes receiving configuration information about resource allocation for an uplink (UL) transmission, the configuration information indicating: allocated resources for an UL transmission, and UL precoding information for the UL transmission on the allocated resources, wherein the UL precoding information indicates: an update precoding matrix V, and basis vectors and coefficients for the update precoding matrix V; determining an UL precoding matrix for the UL transmission based on the update precoding matrix V and a previous UL precoding matrix; and performing UL transmission on the allocated resources using the UL precoding matrix.