Abstract: A method of transmitting information necessary for performing collaborative multi input multi output (MIMO) operation between a mobile station and a base station in order to improve reception performance of the mobile station in a multi-cell environment is provided. The mobile station may receive a feedback channel for the collaborative MIMO which is allocated by a serving base station and transmit a collaborative MIMO indicator including information indicating that the collaborative MIMO is started to the serving base station. In addition, the mobile station may transmit the feedback information of each of the serving base station and a collaborative base station to the serving base station through the feedback channel, and the serving base station may transmit the feedback information to the collaborative base station via a backbone network. The mobile station may receive the collaborative MIMO supported by the serving base station and the collaborative base station.

Abstract: Provided is a spatial phase shifting interferometer using a multi wavelength. More particularly, provided is a spatial phase shifting interferometer using a multi wavelength capable of more rapidly measuring a precise shape of a measurement object by simultaneously oscillating laser having different wavelengths and passing oscillated laser through a beam splitter and a lens to analyze an interference fringe of the measurement object.

Abstract: A method for transmitting feedback information in a codebook-based multiple-input multiple-output (MIMO) system is disclosed. To transmit the feedback information, a signal is received to discern channel characteristics of the received signal, and a codebook is updated using an extended matrix including a plurality of vector components and using previous feedback information. Feedback information is selected for transmission from the updated codebook in consideration of the channel characteristics of the received signal.

Abstract: A method for detecting signals based on despreading and a signal transmitting method for the same are provided. Signals are spread according to the size of at least one spreading band, which is determined in consideration of a correlation degree of a frequency band in a communication system. A reception side which receives the signals detects the signals after de-spreading with respect to signals which are spread in a frequency band having a correlation degree equal to or greater than a predetermined level as a spreading band, among the reception signals. Thus, the dimension of the detected signals can be decreased.

Abstract: A method of transmitting feedback information in a multiple antenna system is provided. The method includes selecting at least one subband selected from a plurality of subbands according to subband preset information, the subband preset information being a preset on data processing settled for each of the plurality of subbands, and transmitting a subband index of the selected subband. Only a subband index is fed back instead of separately transmitting a precoder index or a modulation and coding scheme (MCS) level index to each UE, thereby reducing feedback overhead.

Abstract: A method of transmitting and receiving feedback information in a multi-cell based wireless communication system using FFR, a mobile station apparatus therefore and a base station apparatus therefore are disclosed. A mobile station is able to obtain FFR configuration information including configuration information on at least one frequency partition to which a corresponding FFR is applied per cell ID. And, the mobile station is able to transmit PMI information to a serving base station using the obtained FFR configuration information. In this case, the PMI information is specifically restricted or recommended by the mobile station among PMIs (precoding matrix indexes) used by at least one neighbor cell in an allocated specific frequency partition.

Abstract: A method for reducing inter-cell interference and a method for transmitting a signal by a collaborative MIMO scheme, in a communication system having a multi-cell environment are disclosed. An example of a method for transmitting, by a mobile station, precoding information in a collaborative MIMO communication system includes determining a precoding matrix set including precoding matrices of one more base stations including a serving base station, based on signal strength of the serving base station, and transmitting information about the precoding matrix set to the serving base station. A mobile station in an edge of a cell performs a collaborative MIMO mode or inter-cell interference mitigation mode using the information about the precoding matrix set collaboratively with neighboring base stations.

Abstract: A method of data transmission from a transmitter of a wireless communication system which uses multiple antennas comprises receiving identification information of a precoding matrix from a receiver, the precoding matrix being selected from a codebook generated using a plurality of first matrices generated by multiplying a discrete fourier transform (DFT) matrix by each of a plurality of phase shift matrices; precoding data to be transmitted, by using a precoding matrix indicated by the identification information; and transmitting the precoded data to the receiver by using the multiple antennas.

Abstract: A method of transmitting control information includes dividing frequency bandwidth into ranges to which the same PMI (precoding matrix index) is applied, obtaining multiple antenna information by the range to which the same PMI is applied and transmitting the multiple antenna information. Since multiple antenna information is transmitted by the unit of a range to which the same PMI is applied, radio resources allocated for transmitting the multiple antenna information may be reduced, thereby enhancing data transmission efficiency.

Abstract: A frequency-stabilized laser apparatus and a method for stabilizing the frequency of a laser are disclosed. A semiconductor laser emits a beam. An external reflector has a resonance frequency and feeds back the emitted beam to the semiconductor laser if the frequency of the emitted beam is equal to the resonance frequency. An interference signal generator generates an interference signal for detecting the wavelength of the emitted beam and a controller detects the wavelength of the beam from the generated interference signal. According to the frequency-stabilized laser apparatus and the method for stabilizing the frequency of the laser, it is possible to stabilize the frequency of the beam emitted from the semiconductor laser and output the beam having the stable frequency for a long period of time.

Abstract: A shape measurement apparatus and method using a laser interferometer are disclosed. The shape measurement apparatus includes a plurality of laser devices, which generate beams, emit a beam of a specific frequency from among the generated beams, and output interference signals for detecting wavelengths of the generated beams, and a controller for detecting the wavelengths of the generated beams from the outputted interference signals, and controlling the laser devices on the basis of the detected wavelengths. The optical unit projects the beam of the laser device on a target object, and generates an interference pattern of the object. Several shutters are closed and opened. If the shutters are closed, they prevent the beam of each laser device to be projected on the optical unit. An image pickup unit captures the interference pattern.

Abstract: A method for transmitting and receiving a precoded signal in a Multi-Input Multi-Output (MIMO) communication system is provided. In the method, a preceding matrix is selected from a codebook including one or more preceding matrices of each rank, each of the preceding matrices including a unitary matrix modified by an antenna selection element. A signal for transmission is then precoded by applying the selected preceding matrix to the signal for transmission and the precoded signal is transmitted through a selected antenna.

Abstract: A data transmission method for multiple users having multiple receive antennas is provided. The method includes selecting a receive antenna among the multiple receive antennas for each user, performing DPC (Dirty Paper Coding) from the multiple transmit antennas to the receive antenna and transmitting a transmission signal on which the DPC is performed. Since DPC is implemented through a receive antenna selected among multiple receive antennas, complexity is not much increased although the DPC is applied to a MIMO system.

Abstract: According to one embodiment, a method of receiving signals from a transmitter having a plurality of antennas includes: receiving the signals from the transmitter; selecting a precoding matrix based on a multiplexing rate (R) by selecting R column vectors from a single matrix corresponding to a maximum multiplexing rate, wherein the maximum multiplexing rate corresponds to a number (Nt) of the plurality of antennas, wherein each column vector of a first precoding matrix corresponding to a first multiplexing rate is included as a part of column vectors of a second precoding matrix corresponding to a second multiplexing rate when the second multiplexing rate is greater than the first multiplexing rate; and processing the received signals using the selected precoding matrix.

Abstract: A feedback method for a multi-antenna system is disclosed. The feedback method for use in the multi-antenna system can reduce an amount of transmission (Tx) feedback information associated with a precoding matrix (i.e., a codebook). For example, a single codebook may include precoding matrixes associated with several ranks. A basic matrix constructing the precoding matrix is extended to a frequency axis, such that it can be used as a Cyclic Delay Diversity (CDD) structure.

Abstract: A method for reducing inter-cell interference and a method for transmitting a signal by a collaborative MIMO scheme, in a communication system having a multi-cell environment are disclosed. An example of a method for transmitting, by a mobile station, precoding information in a collaborative MIMO communication system includes determining a precoding matrix set including precoding matrices of one more base stations including a serving base station, based on signal strength of the serving base station, and transmitting information about the precoding matrix set to the serving base station. A mobile station in an edge of a cell performs a collaborative MIMO mode or inter-cell interference mitigation mode using the information about the precoding matrix set collaboratively with neighboring base stations.

Abstract: A method for reducing inter-cell interference and a method for transmitting a signal by a collaborative MIMO scheme, in a communication system having a multi-cell environment are disclosed. An example of a method for transmitting, by a mobile station, precoding information in a collaborative MIMO communication system includes determining a precoding matrix set including precoding matrices of one more base stations including a serving base station, based on signal strength of the serving base station, and transmitting information about the precoding matrix set to the serving base station. A mobile station in an edge of a cell performs a collaborative MIMO mode or inter-cell interference mitigation mode using the information about the precoding matrix set collaboratively with neighboring base stations.

Abstract: A method for transmitting feedback information in a codebook-based multiple-input multiple-output (MIMO) system is disclosed. For example, a method for transmitting beamforming information in a MIMO system using a codebook-based beamforming scheme includes receiving a signal and estimating a reception channel, and transmitting beamforming information selected through the estimated channel information from a codebook which is updated using phase shift matrices having a phase value as a parameter and using previous beamforming information.

Abstract: A method for reducing inter-cell interference and a method for transmitting a signal by a collaborative MIMO scheme, in a communication system having a multi-cell environment are disclosed. An example of a method for transmitting, by a mobile station, precoding information in a collaborative MIMO communication system includes determining a precoding matrix set including precoding matrices of one more base stations including a serving base station, based on signal strength of the serving base station, and transmitting information about the precoding matrix set to the serving base station. A mobile station in an edge of a cell performs a collaborative MIMO mode or inter-cell interference mitigation mode using the information about the precoding matrix set collaboratively with neighboring base stations.

Abstract: A method for reducing inter-cell interference and a method for transmitting a signal by a collaborative MIMO scheme, in a communication system having a multi-cell environment are disclosed. An example of a method for transmitting, by a mobile station, precoding information in a collaborative MIMO communication system includes determining a precoding matrix set including precoding matrices of one more base stations including a serving base station, based on signal strength of the serving base station, and transmitting information about the precoding matrix set to the serving base station. A mobile station in an edge of a cell performs a collaborative MIMO mode or inter-cell interference mitigation mode using the information about the precoding matrix set collaboratively with neighboring base stations.