Aspects of the subject disclosure may include, for example, receiving sounding reference signal (SRS) symbols from antenna elements of each of multiple modular antenna arrays, wherein the multiple modular antenna arrays are operatively combined to form a coherent antenna system, performing an uplink (UL) channel estimation and a downlink (DL) channel estimation, across a plurality of physical resource blocks (PRBs), based on the SRS symbols, calculating, for the antenna elements, a plurality of uplink (UL) combining weights based on the UL channel estimation and a plurality of downlink (DL) precoder weights based on the DL channel estimation, and causing the plurality of UL combining weights and the plurality of DL precoder weights to be applied to the antenna elements, thereby adjusting beamforming of the coherent antenna system. Other embodiments are disclosed.

Disclosed are devices and methods for selecting, at an antenna reflector, electromagnetic waves with a certain polarization and frequency and rejecting electromagnetic waves with different polarizations and/or frequencies. In one aspect, a directional antenna includes a shaped reflector surface with a series of conforming layers attached to the surface. The layers include a reflecting layer that causes reflection of electromagnetic waves at a specific frequency and polarization. Underneath the reflecting layer is a frequency selective surface (FSS) layer that absorbs electromagnetic waves not at the specific frequency or polarization which pass through the reflecting layer. Underneath the absorbing layer is a conductive layer.

A wireless device and a method therein for assisting in precoder selection for wireless communication with a Radio Node (RN), and a RN for performing precoder selection for wireless communication with a wireless device. The wireless device is configured with a set of precoders. The wireless device determines a subset of precoders out of the set of precoders; and transmits, to the RN, at least one Sounding Reference Signal (SRS) precoded with a respective at least one precoder comprised in the subset. The RN receives, from the wireless device, at least one SRS precoded with a respective at least one precoder comprised in a subset of precoders; and transmits, to the wireless device, a signal indicative of a selected precoder to be used for a transmission to the RN, wherein the selected precoder is indirectly selected based on the received at least one SRS.

The present invention relates to a method for transmitting, by a base station, a downlink signal using a plurality of transmission antennas comprises the steps of: applying a precoding matrix indicated by the PMI, received from a terminal, in a codebook to a plurality of layers, and transmitting the precoded signal to the terminal through a plurality of transmission antennas. Among precoding matrices included in the codebook, a precoding matrix for even number transmission layers can be a 2×2 matrix containing four matrices (W1s), the matrix (W1) having rows of a number of transmission antennas and columns of half the number of transmission layers, the first and second columns of the first row in the 2×2 matrix being multiplied by 1, the first column of the second row being multiplied by coefficient “a” of a phase, and the first column of the second row being multiplied by “−a”.

A base station capable of communicating with a user equipment (UE) includes a transceiver configured to transmit downlink signals containing first and second antenna numbers, first and second oversampling factors indicating respective oversampling rates in first and second dimensions for each beam group, first and second quantities of beams indicating respective quantities of beams in the first and second dimensions for each beam group, and first and second beam skip numbers indicating respective differences of leading beam indices of two adjacent beam groups in the first and second dimensions, receive uplink signals containing a plurality of precoding matrix indicators (PMIs) from the UE. Other embodiments including methods and UEs and methods are disclosed.

The present disclosure relates to an antenna arrangement and a method for radio transmission. The antenna arrangement comprises a pre-coder (310) connected to an antenna array (320). The antenna array (320) comprises a number N of antenna elements a.sub.i (321), i=1, 2, . . . , N, each antenna element a.sub.i being configured to receive a respective transmit signal component TX.sub.i from the pre-coder (310). The pre-coder (310) is configured to receive a number M<N of independent data streams s.sub.j, j=1, 2, . . . , M, and to generate the N transmit signal components, wherein the generating comprises suppressing a correlation between any two transmit signal components TX.sub.i1 and TX.sub.i2 received by antenna elements a.sub.i1 and a.sub.i2 arranged adjacently in the antenna array (320).

There is disclosed a method of operating a transmitter arrangement for a wireless communication network, the transmitter arrangement adapted for beamforming. The method comprises determining a maximum power level mask for the power of transmission and/or beams in a critical angular interval, the maximum power level mask covering at least the critical angular interval and controlling beamforming based on the maximum power level mask.

The present disclosure provides a method and device for 3D MIMO communication in a UE and a base station. In an embodiment, in a first step, a UE receives a downlink reference signal in a first RS resource and a second RS resource; in a second step, the UE determines a target RS resource, wherein the target RS resource is the first RS resource or the second RS resource; and in a third step, the UE feeds back a first CI and a first index, wherein the first RS resource comprises N1 RS ports, the second RS resource comprises N2 RS ports, a reference RS of the first CI is the target RS resource, the first index indicates the target RS resource, N1 is a positive integer greater than 1, and N2 is a positive integer greater than 1. By using the technical scheme provided in the present invention, a UE feeds back the most effective CI information by using limited air-interface resources, and therefore overheads of the air-interface resources are reduced or the feedback efficiency of the CI is improved.

A method for reporting a channel state for a downlink channel according to an embodiment of the present invention, which is performed by a terminal, may comprise the steps of: receiving, from a base station, restriction information on a precoding matrix in a code book, wherein the restriction information on the precoding matrix is represented by one or more bit values; calculating a channel state value for the downlink channel using the limitation information, and transmitting the calculated channel state value to the base station.

Methods and apparatuses enabling uplink multiple-input multiple-output (MIMO) are provided. A user equipment (UE) includes a transceiver and a processor operably connected to the transceiver. The transceiver is configured to receive an uplink (UL) grant for an UL transmission. The processor is configured to decode a precoding information field in downlink control information (DCI) associated with the UL grant. The precoding information field includes at least one precoding matrix indicator (PMI) corresponding to a plurality of precoders. The transceiver is further configured to precode a data stream according to the precoders indicated by the precoding information field and transmit the precoded data stream on an UL channel.