A method, system and apparatus for realizing FD_MIMO in codebook-based transmissions. The method, system and apparatus include the combing of one or more horizontal codebooks and one or more vertical codebooks. A 2D beamformer for downlink transmissions is generated based on the combination of the one or more horizontal codebooks and one or more vertical codebooks.

Some embodiments of this disclosure provide a method for determining an index of an orthogonal basis vector and a device. The method includes: receiving position information, where the position information is associated with an orthogonal basis vector; and determining at least one first index set based on the position information, where the first index set represents a set of column indices of a plurality of orthogonal basis vectors in an orthogonal basis matrix.

Methods, systems, and devices for wireless communications are described. A first wireless device may receive a request for beamforming information associated with line-of-sight (LoS) multiple input multiple output (MIMO) communication from a second wireless device. The first wireless device may generate a channel estimation matrix for a channel between rectangular antenna arrays of the respective wireless devices, the channel estimation matrix including one or more quadratic terms for the LoS MIMO communication. The first wireless device may generate a first sub-matrix and a second sub-matrix based on the channel estimation matrix. The first wireless device may transmit an indication of a set of precoders for the LoS MIMO communication, the set of precoders based on a symmetry associated with the first and second sub-matrices, and may receive the LoS MIMO communication from the second wireless device based on the set of precoders.

A codebook subset restriction configuration can be received (410) from a network entity. A set of reference signals can be received (420) from the network entity. A set of frequency domain coefficients can be defined (430). The set of frequency domain coefficients can be an element of a discrete Fourier transform-compression codebook. The set of frequency domain coefficients can be generated (440) based on at least the restriction of the function of the amplitude restriction ratio of each beam in the set of restricted beams. At least one channel state information report containing the set of frequency domain coefficients can be transmitted (450).

A method for operating a user equipment (UE) comprises receiving configuration information about a channel state information (CSI) report, the configuration information including a number of radio remote heads (RRHs), N.sub.RRH>1; selecting a subset of RRHs from the N.sub.RRH RRHs independently for each subband (SB); determining the CSI report including an indicator indicating the selected subset of RRHs for each SB; and transmitting the CSI report including the indicator indicating the selected subset of RRHs for each SB.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE measures, at a first time point, a first set of reference signals to determine a first set of values corresponding to a set of CSI parameters. The UE determines value differences between the first set of values and a set of reference values corresponding to the set of CSI parameters. The UE sends a first CSI report including variation indicators indicating the value differences.

Provided are an information feedback method, terminal, base station, a storage medium, and an electronic device. The method includes: decomposing a channel state information (CSI) matrix H to obtain a matrix U.sub.d and a matrix V.sub.d, where U.sub.d is a matrix having d columns, and every two column vectors are mutually orthogonal; and V.sub.d is a matrix having d columns, and every two column vectors are mutually orthogonal; and feeding back amplitude and phase information of elements in U.sub.d including d left eigenvectors and/or amplitude and phase information of elements in V.sub.d including d right eigenvectors.

A method, performed by a User Equipment (UE), includes receiving, from a base station (BS), a radio resource control (RRC) message comprising an information for configuring a Hybrid Automatic Repeat reQuest-ACKnowledge (HARQ-ACK) codebook list, first downlink control information (DCI) and second DCI; determining whether a size difference exists between a first downlink assignment index (DAI) field of the first DCI and a second DAI field of the second DCI; and inserting at least one bit with a zero value into one of the first DAI field and the second DAI field when the size difference between the first DAI field of the first DCI and the second DAI field of the second DCI is determined, wherein the HARQ-ACK codebook list includes a first HARQ-ACK codebook indicated by the first DCI and a second HARQ-ACK codebook indicated by the second DCI.

A method includes receiving (402) a plurality of reference signals (301-303) at an antenna port of a communication device (101). Each reference signal (301-303) is sent using a corresponding precoder. The precoder is selected from a first set of precoders. The method further includes determining (403) a channel estimate based on the received plurality of reference signals (301-303), and selecting (404) a precoder from a second set of precoders based on the determined channel estimate. The second set of precoders comprises at least one precoder in addition to the precoders of the first set of precoders. The method includes sending (405) an indication (304) relating to the selected precoder.

Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) or a base station, or both, may generate a set of orthogonal sequences that the UE may use to convey a payload of a number of bits based on a product of an orthogonal matrix and a cell-specific sequence. The UE or the base station, or both, may select a subset of the set of orthogonal sequences based on the number of bits in the payload, and the UE may construct a codebook including the subset of orthogonal sequences. The UE may select an orthogonal sequence from the constructed codebook based on the bits in the payload. The UE may transmit the payload including the number of bits to the base station using the selected orthogonal sequence.