User equipment for implementing 3D MIMO (3-Dimensional Multiple-Input Multiple-Output) communication includes: a transmission and reception unit configured to transmit and receive radio signals to/from a base station in the 3D MIMO communication; and a codebook management unit configured to have a first codebook and a second codebook. The codebook management unit determines a 3D codebook for the 3D MIMO communication by combining the first codebook with the second codebook, and the transmission and reception unit feeds the first codebook and the second codebook serving as a basis of calculating the determined 3D codebook back to the base station.

A method for a channel state information (CSI) feedback. The method comprises receiving CSI feedback configuration information for the CSI feedback including a spatial channel information indicator based on a linear combination (LC) codebook, wherein the spatial channel information comprises at least one of a downlink channel matrix, a covariance matrix of the downlink channel matrix, or at least one eigenvector of the covariance matrix of the downlink channel matrix; deriving the spatial channel information indicator using the LC codebook that indicates a weighted linear combination of a plurality of basis vectors or a plurality of basis matrices as a representation of at least one of a downlink channel matrix, a covariance matrix of the downlink channel matrix, or at least one eigenvector of the covariance matrix of the downlink channel matrix; and transmitting over an uplink channel, the CSI feedback including the spatial channel information indicator.

The present invention relates to a wireless communication system and, more specifically, to a method and device for reporting channel state information (CSI). The method by which a terminal in a wireless communication system reports CSI, according to one embodiment of the present invention, can comprise the steps for: receiving a reference signal from a base station; and reporting, to the base station, the CSI generated by using the reference signal. When the CSI for a two-dimensional antenna structure defined by a first domain and a second domain includes a channel quality indicator (CQI) for the two-dimensional antenna structure without including a precoding matrix indicator (PMI) for the two-dimensional antenna structure, the CQI can be calculated on the basis of the tilting in the second domain.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may transmit a first physical random access channel (PRACH) transmission that includes a first random access (RA) preamble to a base station. The apparatus may determine whether to transmit to the base station a second PRACH transmission that is concurrent with the first PRACH transmission in time, wherein the second PRACH includes a second RA preamble. The apparatus may transmit, to the base station, the second PRACH transmission that includes the second RA preamble when the second PRACH transmission is determined to be transmitted. The first RA preamble and the second RA preamble may be different, and the first RA preamble and the second RA preamble may be concurrently transmitted in a same PRACH occasion or in different PRACH occasions that overlap in time.

A method for transmitting signals to a user equipment at a base station in a wireless communication system is disclosed. The method includes generating a user equipment specific reference signal sequence for the user equipment, determining transmission resources for mapping the user equipment specific reference signal sequence, based on a vertical sector in which the user equipment is located, mapping the user equipment specific reference signal sequence to the determined transmission resources, and transmitting the user equipment specific reference signal sequence to the user equipment using a second-dimensional planar antenna.

A method and a device for determining parameters of a precoder in a wireless communication system are disclosed. According to one aspect, a method includes selecting a subset of beams corresponding to a plurality of orthogonal beams; obtaining power levels of the selected subset of beams for generating a first factor of the precoder and obtaining phases of the selected subset of beams for generating a second factor, wherein the first factor and the second factor are part of the parameters of the precoder.

Channel state information (CSI) feedback in a wireless communication system is disclosed. A precoding matrix is generated for multi-antenna transmission based on precoding matrix indicator (PMI) feedback, wherein the PMI indicates a choice of precoding matrix derived from a matrix multiplication of two matrices from a first codebook and a second codebook. In one embodiment, the first codebook comprises at least a first precoding matrix constructed with a first group of adjacent Discrete-Fourier-Transform (DFT) vectors. In another embodiment, the first codebook comprises at least a second precoding matrix constructed with a second group of uniformly distributed non-adjacent DFT vectors. In yet another embodiment, the first codebook comprises at least a first precoding matrix and a second precoding matrix, where said first precoding matrix is constructed with a first group of adjacent DFT vectors, and said second precoding matrix is constructed with a second group of uniformly distributed non-adjacent DFT vectors.

Embodiments disclosed herein include distributed antenna systems (DASs) supporting expanded, programmable communications services distribution to remote communications service sector areas. In one embodiment, the DAS includes a first programmable switch for distributing downlink communications signals into one or more communications service sector sets. The DAS further includes a second programmable switch configured to distribute the one or more communications service sector sets to one or more remote communications service sector areas. A configurable extender module is also included to provide expanded routing of communications service sector sets in the DAS. In this manner, the DAS is programmable to allow any combination of communications service sector sets and expanded communications service sector sets from any number of different base stations to be routed to any combination of remote communications service sector areas and expanded remote communications service sector areas, based on capacity needs and capability of the DAS.

Disclosed are a spatial multiplexing method and apparatus using polarization in a multi-beam system.

As the spatial multiplexing method using polarization in a multi-beam system, an embodiment of the present invention provides a spatial multiplexing method including determining different phases and different polarizations to be applied to a first beam and a second beam, precoding a signal so that the first beam and the second beam have the determined different phases, and converting polarization of the precoded signal so that the first beam and the second beam have the determined different polarizations.

Provided is a transmission control apparatus that determine a first phase difference for a phase difference between an electric wave output by a first antenna and an electric wave output by a second antenna, and for a phase difference between an electric wave output by a third antenna and an electric wave output by a fourth antenna, based on a determined polarization characteristic; determines a second phase difference for a phase difference between the electric wave output by the first antenna and the electric wave output by the third antenna and for a phase difference between the electric wave output by the second antenna and the electric wave output by the fourth antenna, based on the determined beam direction; and controls phases of the electric waves output by the first to fourth antennas, according to the first and second phase differences.