Abstract: There is a provided a method for deciding transmission power in order to transmit at least one of secret data and non-secret data. The method may comprise: determining whether data to be transmitted by a transmitting device is sensitive to a delay; determining whether both the secret data and the non-secret data are required to be simultaneously transmitted when the data to be transmitted is sensitive to the delay; and applying different weights to the secret data and the non-secret data and deciding transmission power to maximize a total channel capacity according to the application, when it is determined that both the secret data and the non-secret data are required to be transmitted.

Abstract: A method and apparatus for secured data transmission is provided. The base station determines a first precoding matrix based on channel information of an eavesdropper. The base station determines a second precoding matrix and a third precoding matrix. The base station generates the secure data by precoding first user data for a target user with the first precoding matrix and the second precoding matrix. The base station transmits the secure data signal to the target user. The second precoding matrix is determined based on the first precoding matrix and the first channel information. The third precoding matrix is determined based on the first channel information and the second channel information.

Abstract: A communication apparatus and method using a massive multiple input multiple output (MIMO) is disclosed, the method including measuring a transmission capacity between terminals disposed in a cell and a base station when a number of terminals disposed in the cell of the base station is greater than a number of terminals to be supported by the base station, and selecting at least one terminal for maximizing a network capacity from among terminals disposed in the cell based on the transmission capacity and the number of terminals to be supported by the base station.

Abstract: There is a provided a method for deciding transmission power in order to transmit at least one of secret data and non-secret data. The method may comprise: determining whether data to be transmitted by a transmitting device is sensitive to a delay; determining whether both the secret data and the non-secret data are required to be simultaneously transmitted when the data to be transmitted is sensitive to the delay; and applying different weights to the secret data and the non-secret data and deciding transmission power to maximize a total channel capacity according to the application, when it is determined that both the secret data and the non-secret data are required to be transmitted.

Abstract: A method and apparatus for secured data transmission is provided. The base station determines a first precoding matrix based on channel information of an eavesdropper. The base station determines a second precoding matrix and a third precoding matrix. The base station generates the secure data by precoding first user data for a target user with the first precoding matrix and the second precoding matrix. The base station transmits the secure data signal to the target user. The second precoding matrix is determined based on the first precoding matrix and the first channel information. The third precoding matrix is determined based on the first channel information and the second channel information.

Abstract: In a multi-input multi-output communication system receiving signals transmitted through a plurality of transmission antennas by using a plurality of reception antennas, a matrix determining a position of a symbol to be detected from a received signal is calculated at a first symbol detection step, and from the subsequent step, a matrix at the current step is acquired through a simple relationship from the matrix calculated at the previous step to determine a position of a symbol to be detected.

Abstract: Disclosed is a method of detecting signals at a receiver of a communication system with a multiple input multiple output antenna. With the signal detection method, a square of the distance between a received signal vector and a channel status-considered transmission symbol vector is calculated first, and the square of the distance is then classified into first and second components. The first component is minimized to calculate a plurality of first soft symbol estimates. A solution set of the first component is calculated on the basis of the plurality of first soft symbol estimates. The second component is minimized to calculate a plurality of second soft symbol estimates. A solution set of the second component is calculated on the basis of the plurality of second soft symbol estimates. A final solution set is calculated by doing the sum of the first component solution set and the second component solution.

Abstract: The present invention relates to a transmission symbol detection method in a multiple antenna system. In the present invention, when a channel matrix is estimated through channel estimation, a receiving side calculates a Q matrix and an R matrix through QR decomposition that is more simplified than a typical QR decomposition from an augmented channel matrix that includes the estimated channel matrix. In addition, the receiving side detects symbols having the minimum Euclidean metric by using the two matrixes, as transmission symbols.

Abstract: In a multi-input multi-output communication system receiving signals transmitted through a plurality of transmission antennas by using a plurality of reception antennas, a matrix determining a position of a symbol to be detected from a received signal is calculated at a first symbol detection step, and from the subsequent step, a matrix at the current step is acquired through a simple relationship from the matrix calculated at the previous step to determine a position of a symbol to be detected.

Abstract: Disclosed is a method of detecting signals at a receiver of a communication system with a multiple input multiple output antenna. With the signal detection method, a square of the distance between a received signal vector and a channel status-considered transmission symbol vector is calculated first, and the square of the distance is then classified into first and second components. The first component is minimized to calculate a plurality of first soft symbol estimates. A solution set of the first component is calculated on the basis of the plurality of first soft symbol estimates. The second component is minimized to calculate a plurality of second soft symbol estimates. A solution set of the second component is calculated on the basis of the plurality of second soft symbol estimates. A final solution set is calculated by doing the sum of the first component solution set and the second component solution.

Abstract: The present invention relates to a transmission symbol detection method in a multiple antenna system. In the present invention, when a channel matrix is estimated through channel estimation, a receiving side calculates a Q matrix and an R matrix through QR decomposition that is more simplified than a typical QR decomposition from an augmented channel matrix that includes the estimated channel matrix. In addition, the receiving side detects symbols having the minimum Euclidean metric by using the two matrixes, as transmission symbols.

Abstract: The present invention relates to a method of detecting a space-time code in a mobile communication system. When detecting a space-time code B for a plurality of transmitting antennas, an ML (maximum likelihood) metric, which is generally calculated by using a specific structure of a matrix B, is defined as a new ML metric by reducing a variable of the ML metric. Two dependent sphere decoding processes are performed and an intersection of the decoding results is calculated, and a signal is detected from the ML metric. Therefore, since detection of the space-time code B for the plurality of transmitting antennas is performed by using the newly defined ML metric, an amount of matrix calculated can be reduced, and a calculation amount can be reduced by performing the two dependent sphere decoding processes. Further, since a detection order of symbols is changed according to a channel situation, it is possible to improve the performance of the system.

Abstract: A method of controlling the bit error rate of packets in a wired or wireless communication system controls differently the target bit error rate (BER) of a video packet depending on the state of importance after determining importance of the video information in the video packet by making the target BER of the important packet smaller and the target BER of the less important packet larger.