The present invention relates to a method and an apparatus for transmitting, by a base station, a reference signal in a wireless communication system supporting a multi-antenna consisting of a plurality of horizontal domain antennas and a plurality of vertical domain antennas. Specifically, the method comprises the steps of: configuring, as a cell-specific reference signal (CRS) port, M first antenna ports among a total of N antennas that the base station has (where N and M are positive integers, N>M); transmitting a CRS using the M first antenna ports and transmitting a demodulation reference signal (DM-RS) using 0 second antenna ports (where 0 is a positive integer, N>O), to a terminal; and receiving channel measurement information using the CRS and the DM-RS which is fed back from the terminal.

The present invention relates to a base station in a wireless communication system which supports multi-antennas with multiple horizontal domains and multiple vertical domains. Particularly, the present invention comprises: a radio frequency unit and a processor, wherein the radio frequency unit comprises a first radio frequency (RF) chain and a second radio frequency (RF) chain which are connected to antenna elements corresponding to multiple vertical antennas with specific horizontal domains, wherein the processor, connected to the radio frequency unit, is configured to transmit reference signals, and wherein the first RF chain and the second RF chain are configured for different reference signals.

A method for selecting a precoder from a codebook for a channel matrix H and an apparatus. The method includes determining, by a processor, a reference precoder V for the channel H and a phase rotation for V; for all codewords W from a codebook, determining, by the processor, phase rotations for W and phase distances based on differences between phases of elements of V and W; and selecting, by the processor, the codeword W with a minimum phase distance, wherein H has a size of N.sub.R×N.sub.T, N.sub.R is a number of receive antennas, N.sub.T is a number of transmit antennas, V has a size of N.sub.T×L, and L is a number of data layers transmitted simultaneously.

A method implemented in a base station used in a wireless communications system is disclosed. The method comprises having 1-layer, 2-layer, 3-layer, and 4-layer codebooks for 4 transmit antenna (4TX) transmission, each codebook including a plurality of precoding matrices, (precoding data with one of the plurality of precoding matrices, and transmitting, to a user equipment, the precoded data, wherein each of the 1-layer and 2-layer codebooks comprises a first codebook and a second codebook, and wherein each precoding matrix in the first codebook comprises a first index and a second index. Other apparatuses, systems, and methods also are disclosed.

A method for generating a data sample in a first frequency band from measurements in a second frequency band. The method includes obtaining a first plurality of samples, obtaining a second plurality of samples, obtaining a mapping model based on the first plurality of samples and the second plurality of samples, obtaining a third plurality of samples, and obtaining the data sample based on the mapping model and the third plurality of samples. Obtaining the first plurality of samples includes measuring a first frequency response of an environment in the first frequency band. Obtaining the second plurality of samples includes measuring a second frequency response of the environment in the second frequency band. Obtaining the third plurality of samples includes measuring a third frequency response of the environment in the second frequency band. Obtaining the data sample includes applying the mapping model on the third plurality of samples.

There is provided two-dimensional beam forming using a two dimensional antenna array. The beam forming comprises alternatingly transmitting a first set of reference signals for channel state information using a two-dimensional antenna array as a first essentially linear array and as a second essentially linear array substantially perpendicular to the first linear array, respectively. When used as the first linear array one reference signal of the first set per virtual antenna port in said first linear array is transmitted. When used as the second linear array one reference signal of the first set per virtual antenna port in the second linear array is transmitted.

A method performed by a base station of enabling a User Equipment, UE, to determine a precoder codebook in a wireless communication system is provided. The base station transmits (303) to the UE, information regarding precoder parameters enabling the UE to determine the precoder codebook. The precoder parameters are associated with a plurality of antenna ports of the base station. The precoder parameters relate to a first dimension and a second dimension of the precoder codebook. The plurality of antenna ports comprises a number NT of antenna ports that is a function of a number Nh of antenna ports in the first dimension, and a number Nv of antenna ports in the second dimension.

A terminal is disclosed that includes a processor that performs channel measurement based on a first Channel State Information-Reference Signal (CSI-RS) and performs channel measurement based on a second CSI-RS; and a transmission section that transmits a first Channel State Information (CSI) feedback based on the first CSI-RS and a second CSI feedback based on the second CSI-RS. Additionally, when the first CSI-RS is an un-precoded CSI-RS, the first CSI feedback only includes a part of information of CSI feedback based on the un-precoded CSI-RS that is a precoding matrix indicator (PMI) or are the PMI and a rank indicator (RI). In another aspect, a CSI feedback method for a terminal is also disclosed.

Methods and corresponding apparatuses for wireless communication are disclosed. The method for wireless communication includes dividing a two-dimensional antenna array to a plurality of sub-arrays, mapping the two-dimensional antenna array into a one-dimensional vertical channel state information reference signal (CSI-RS) port array for receiving elevation CSI feedback and a one-dimensional horizontal CSI-RS port array for receiving azimuth CSI feedback, and transmitting one or more elevation CSI-RS from the one-dimensional vertical CSI-RS port array and one or more azimuth CSI-RS from the one-dimensional horizontal CSI-RS port array. Methods and corresponding apparatuses for CSI feedback mechanism are also disclosed.

An antenna connection detection method and apparatus are provided, to detect whether a connection sequence between communications interfaces of a network side device and antenna elements is incorrect. The method includes that a network side device receives, by using antenna elements connected to a plurality of communications interfaces, reference signals sent by N terminal devices, where N is an integer greater than 0. Then, the network side device determines N channel correlation matrices based on the reference signals sent by the N terminal devices, and then determines, based on the N channel correlation matrices and a preset channel correlation matrix, whether a connection sequence between the plurality of communications interfaces and the antenna elements is incorrect, where one channel correlation matrix is used to represent correlation between transmission channels between the network side device and one terminal device.