Abstract: A data transmission device and a data transmission method are provided. The data transmission device includes: a plurality of front-end modules associated with a plurality of antennas, respectively; and a controller configured to select a front-end module to be used for data communication from among the plurality of front-end modules, wherein the controller is configured to: determine a temperature of each of the plurality of front-end modules; and select, from among the plurality of front-end modules, a front-end module having a temperature lower than or equal to a threshold temperature and corresponding to a maximum received power of a receiving device, among received powers of the receiving device corresponding to the plurality of front-end modules, and wherein each of the received powers of the receiving device is obtained based on a specific absorption rate (SAR) requirement or a maximum permissible exposure (MPE) requirement of a corresponding front-end module.

Abstract: Disclosed are a method and apparatus for processing a transmission signal using a window function that changes a spectrum characteristic of a symbol. A transmission apparatus includes a symbol generator that generate a plurality of consecutive symbols, and a symbol windowing processor that is coupled with the symbol generator. The symbol windowing processor applies a first window function and a third window function that uses a difference between the first window and a second window, and changes a spectrum characteristic of each of the plurality of consecutive symbols, and processes neighboring symbols from among the plurality of consecutive symbols of which spectrum characteristics are changed, such that the symbols partially overlap one another.

Abstract: Disclosed are a method and apparatus for processing a transmission signal using a window function that changes a spectrum characteristic of a symbol. A transmission apparatus includes a symbol generator that generate a plurality of consecutive symbols, and a symbol windowing processor that is coupled with the symbol generator. The symbol windowing processor applies a first window function and a third window function that uses a difference between the first window and a second window, and changes a spectrum characteristic of each of the plurality of consecutive symbols, and processes neighboring symbols from among the plurality of consecutive symbols of which spectrum characteristics are changed, such that the symbols partially overlap one another.

Abstract: A Spatial Multiplexing Multiple Input Multiple Output (SM-MIMO) communication system, which generates Q and R matrices through QR decomposing a channel matrix in an array order corresponding to an order of transmission antennas of a signal transmission device, determines a detection order of transmission symbols included in a transmission symbol vector, QR decomposes a reception signal vector and generates the QR decomposed reception signal vector as a transformed reception signal vector, substitutes all of transmittable candidate symbols for a transmission symbol corresponding to a first detection order among the transmission symbols and sequentially removes interference in the transformed reception signal vector, detects candidate symbols of transmission symbols corresponding to a remaining detection order from the interference-removed transformed reception signal vector, combines the detected candidate symbols, detects candidate symbol vectors, and calculates Log-Likelihood Ratio values of bits included in

Abstract: An apparatus and method for reducing a Peak-to-Average Power Ratio (PAPR) are provided. The apparatus includes a gain processor for multiplying time signals in paths by gains set for respective paths, a delay processor for delaying gain-multiplied signals in second to last paths except for a first path by time delays set for respective second to last paths, a summer for summing the gain-multiplied signal for the first path received from the gain processor and the delayed signals received from the delay processor, a PAPR processor for measuring a PAPR of the summed signal received from the summer, for comparing the measured PAPR with a target PAPR, and for requesting one or more changes of at least one of the gain and time delay of each path, and a gain delay controller for changing the at least one of the gain and the time delay of each path according to the request received from the PAPR processor and for controlling the gain processor and the delay processor according to the change.

Abstract: A Spatial Multiplexing Multiple Input Multiple Output (SM-MIMO) communication system, which generates a Q matrix and an R matrix through QR decomposing a channel matrix in an array order corresponding to an order of transmission antennas of a signal transmission device, determines a detection order of transmission symbols included in a transmission symbol vector, QR decomposes a reception signal vector and generates the QR decomposed reception signal vector as a transformed reception signal vector, substitutes all of transmittable candidate symbols for a transmission symbol corresponding to a first detection order among the transmission symbols and sequentially removes interference in the transformed reception signal vector, detects candidate symbols of transmission symbols corresponding to a remaining detection order from the interference-removed transformed reception signal vector, combines the detected candidate symbols, detects candidate symbol vectors, and calculates Log-Likelihood Ratio values of bits i

Abstract: Disclosed is an apparatus and a method for effectively allocating frequency resources in a mobile communication system. The method includes: determining a first offset of a preset frequency band from among all frequency bands, determining a second offset corresponding to a symbol unit in the preset frequency band, and allocating frequency resources to data, the frequency resources corresponding to a sum of the first offset and the second offset.

Abstract: An apparatus and method for canceling an interference signal in a broadband wireless communication system are provided. A receiver of a wireless communication system includes at least two receive antennas for receiving a target signal of a serving base station and interference signals of at least one neighbor base station; a channel estimator for estimating channels of the signals received through the receive antennas; and a detector for detecting the target signal using channel estimation values of the received signals. Accordingly, it is possible to reduce error propagation caused by the incorrect estimation and detection of the interference signal. In addition, time delay for detecting/restoring/removing the interference signal does not occur. Moreover, the increase of additional buffers can be prevented. Consequently, the increase of hardware complexity can be prevented.

Abstract: A method and apparatus for processing time windowing to transmit a signal in a Broadband Wireless Access (BWA) communication system based on Orthogonal Frequency Division Multiple Access (OFDMA). A signal of a first interval included in a previous symbol prior to a current symbol is stored as a signal of a previous symbol interval. The current symbol includes a guard interval and an effective symbol interval subsequent to the guard interval. The current symbol is windowed by overlapping the stored signal of the first interval with a signal of a second interval included in the current symbol subsequent to the previous symbol. A windowed signal is transmitted.

Abstract: A Peak-to-Average Power Ratio (PAPR) reduction apparatus and method in an OFDM communication system are provided. In the PAPR reduction method, magnitude and phase components are extracted from transmission sample data. Peaks having magnitude components exceeding a threshold are detected by comparing the extracted magnitude components with the threshold. The highest of the peaks is detected and compared with the threshold. If the highest peak is greater than the threshold, the highest peak is updated.

Abstract: An apparatus and method for reducing a Peak-to-Average Power Ratio (PAPR) are provided. The apparatus includes a gain processor for multiplying time signals in paths by gains set for respective paths, a delay processor for delaying gain-multiplied signals in second to last paths except for a first path by time delays set for respective second to last paths, a summer for summing the gain-multiplied signal for the first path received from the gain processor and the delayed signals received from the delay processor, a PAPR processor for measuring a PAPR of the summed signal received from the summer, for comparing the measured PAPR with a target PAPR, and for requesting one or more changes of at least one of the gain and time delay of each path, and a gain delay controller for changing the at least one of the gain and the time delay of each path according to the request received from the PAPR processor and for controlling the gain processor and the delay processor according to the change.

Abstract: An apparatus and method for canceling an interference signal in a broadband wireless communication system are provided. A receiver of a wireless communication system includes at least two receive antennas for receiving a target signal of a serving base station and interference signals of at least one neighbor base station; a channel estimator for estimating channels of the signals received through the receive antennas; and a detector for detecting the target signal using channel estimation values of the received signals. Accordingly, it is possible to reduce error propagation caused by the incorrect estimation and detection of the interference signal. In addition, time delay for detecting/restoring/removing the interference signal does not occur. Moreover, the increase of additional buffers can be prevented. Consequently, the increase of hardware complexity can be prevented.

Abstract: A Peak-to-Average Power Ratio (PAPR) reduction apparatus and method in an OFDM communication system are provided. In the PAPR reduction method, magnitude and phase components are extracted from transmission sample data. Peaks having magnitude components exceeding a threshold are detected by comparing the extracted magnitude components with the threshold. The highest of the peaks is detected and compared with the threshold. If the highest peak is greater than the threshold, the highest peak is updated.

Abstract: A method and apparatus for processing time windowing to transmit a signal in a Broadband Wireless Access (BWA) communication system based on Orthogonal Frequency Division Multiple Access (OFDMA). A signal of a first interval included in a previous symbol prior to a current symbol is stored as a signal of a previous symbol interval. The current symbol includes a guard interval and an effective symbol interval subsequent to the guard interval. The current symbol is windowed by overlapping the stored signal of the first interval with a signal of a second interval included in the current symbol subsequent to the previous symbol. A windowed signal is transmitted.

Abstract: Disclosed is an apparatus and a method for effectively allocating frequency resources in a mobile communication system. The method includes: determining a first offset of a preset frequency band from among all frequency bands, determining a second offset corresponding to a symbol unit in the preset frequency band, and allocating frequency resources to data, the frequency resources corresponding to a sum of the first offset and the second offset.

Abstract: In a communication system using an Orthogonal Frequency Division Multiple Access (OFDMA) scheme, at least one value mapped to the number of threshold subchannels is compared with the number of subchannels allocated to a signal transmission apparatus in an associated Orthogonal Frequency Division Multiplexing (OFDM) symbol when transmission data including m bits is input. In response to a comparison result, (m?k) bits are generated from the transmission data using at least one of clipping and rounding. The (m?k) bits are converted to an analog signal and the analog signal is transmitted. The number of threshold subchannels is preset to determine whether to use clipping, rounding or both.

Abstract: An apparatus and a method for reducing an error vector magnitude in an orthogonal frequency division multiplexing (OFDM) receiver. The method includes the steps of inputting a receiving symbol including a guard interval and an effective symbol interval following the guard interval, in which a front portion of the guard interval and a rear portion of the effective symbol interval have windowing intervals corresponding to windowing of a transmitter, and replacing a signal of the rear windowing interval with a signal of an interval between the front windowing interval and the effective symbol interval, thereby outputting a signal of the effective symbol interval, which substitutes for a signal of the rear windowing interval, to a fast Fourier transform (FFT) section.