Abstract: The present disclosure provides a method and apparatus for sequentially detecting and decoding multiuser sparse code multiple access (SCMA) signal. A detection method includes selecting a single variable node depending on how much the plurality of variable nodes each use function nodes that connect to updated variable nodes; updating messages passed to the single variable node, based on a function node input message passed to the plurality of function nodes and signals received by the plurality of function nodes through channels; mapping updated messages to a priori information of a channel decoder; inputting the priori information to the channel decoder and thereby obtaining probability information of a symbol for the single variable node; and updating messages passed from the single variable node to one of the plurality of function nodes by applying a weight to the probability information of the symbol for the single variable node.

Abstract: The present disclosure provides a method and apparatus for sequentially detecting and decoding multiuser sparse code multiple access (SCMA) signal. A detection method includes selecting a single variable node depending on how much the plurality of variable nodes each use function nodes that connect to updated variable nodes; updating messages passed to the single variable node, based on a function node input message passed to the plurality of function nodes and signals received by the plurality of function nodes through channels; mapping updated messages to a priori information of a channel decoder; inputting the priori information to the channel decoder and thereby obtaining probability information of a symbol for the single variable node; and updating messages passed from the single variable node to one of the plurality of function nodes by applying a weight to the probability information of the symbol for the single variable node.

Abstract: The present disclosure relates to a method and an apparatus for reducing or eliminating interferences between resource blocks in a transmitter and/or a receiver of a filter bank multicarrier system is provided. According to at least one embodiment, the method comprises performing discrete Fourier transform (DFT) on a data symbol vector to be transmitted thereby generating a DFT-spread data symbol vector, performing a cyclic shift operation on the DFT-spread data symbol vector to arrange a small magnitude element of the DFT-spread data symbol vector at an edge of a resource block allocated to the DFT-spread data symbol vector, and performing filter bank multicarrier (FBMC) modulation on a cyclically shifted DFT-spread data symbol vector.

Abstract: The present disclosure relates to a method and an apparatus for reducing or eliminating interferences between resource blocks in a transmitter and/or a receiver of a filter bank multicarrier system is provided. According to at least one embodiment, the method comprises performing discrete Fourier transform (DFT) on a data symbol vector to be transmitted thereby generating a DFT-spread data symbol vector, performing a cyclic shift operation on the DFT-spread data symbol vector to arrange a small magnitude element of the DFT-spread data symbol vector at an edge of a resource block allocated to the DFT-spread data symbol vector, and performing filter bank multicarrier (FBMC) modulation on a cyclically shifted DFT-spread data symbol vector.

Abstract: Disclosed are dual mode beamforming methods and apparatuses for the same. An exemplary embodiment of the dual mode beamforming method may comprise obtaining a boundary equation generated based on mean channel gains (MCGs) and spatial correlation coefficients (SCCs) for a plurality of antennas of a plurality of base station; obtaining, from the plurality of base stations, MCGs of respective antennas equipped in each of the plurality of base stations and a SCC of a plurality of antennas equipped in at least one base station of the plurality of base stations; and determining a beamforming mode based on the boundary equation, the MCGs and SCCs obtained from the plurality of base stations. Therefore, a co-located beamforming or a distributed beamforming can be performed selectively according to a radio communication environment.

Abstract: Disclosed are dual mode beamforming methods and apparatuses for the same. An exemplary embodiment of the dual mode beamforming method may comprise obtaining a boundary equation generated based on mean channel gains (MCGs) and spatial correlation coefficients (SCCs) for a plurality of antennas of a plurality of base station; obtaining, from the plurality of base stations, MCGs of respective antennas equipped in each of the plurality of base stations and a SCC of a plurality of antennas equipped in at least one base station of the plurality of base stations; and determining a beamforming mode based on the boundary equation, the MCGs and SCCs obtained from the plurality of base stations. Therefore, a co-located beamforming or a distributed beamforming can be performed selectively according to a radio communication environment.

Abstract: Disclosed is a method of cancelling inter-subcarrier interferences in distributed antenna system. A method of cancelling interference performed in a transmitting station may include configuring a least one Alamouti pair by mapping subcarrier to each of input symbols, performing a 2N-point inverse fast Fourier transform (IFFT) on the at least one Alamouti pair, wherein the N is a natural number, and performing a frequency up converting on signals on which the 2N-point IFFT performed. Therefore, the inter-subcarrier interferences can be canceled efficiently.

Abstract: Disclosed are a method of cancelling inter-subcarrier interference in a distributed antenna system, and a device for performing the same. The method of cancelling the interference performed in a receiver includes: generating a first signal and a second signal by performing a fast Fourier transform (FFT) operation on a received signal received from a first transmission antenna and a second transmission antenna; acquiring first symbols by combining the first signal and the second signal; generating a first interference signal and a second interference signal based on the first symbols; generating a third signal by cancelling the first interference signal from the first signal, and generating a fourth signal by cancelling the second interference signal from the second signal; and acquiring second symbols by combining the third signal and the fourth signal.

Abstract: Disclosed are a method for cancelling inter-subcarrier interferences and an apparatus for the same. The method according to an example embodiment may comprise dividing total available subcarriers into a plurality of sub-blocks, composing Alamouti code symbol pairs by mapping input symbols to subcarriers included in each of the plurality of sub-blocks, and performing inverse fast Fourier transform (IFFT) on the Alamouti code symbol pairs. Therefore, inter-subcarrier interferences due to frequency error between transmit antennas of a distributed antenna system or a cooperative transmission apparatus may be cancelled in the frequency selective fading channel environment.

Abstract: Disclosed are a method of cancelling inter-subcarrier interference in a distributed antenna system, and a device for performing the same. The method of cancelling the interference performed in a receiver includes: generating a first signal and a second signal by performing a fast Fourier transform (FFT) operation on a received signal received from a first transmission antenna and a second transmission antenna; acquiring first symbols by combining the first signal and the second signal; generating a first interference signal and a second interference signal based on the first symbols; generating a third signal by cancelling the first interference signal from the first signal, and generating a fourth signal by cancelling the second interference signal from the second signal; and acquiring second symbols by combining the third signal and the fourth signal.

Abstract: Disclosed are a method for cancelling inter-subcarrier interferences and an apparatus for the same. The method according to an example embodiment may comprise dividing total available subcarriers into a plurality of sub-blocks, composing Alamouti code symbol pairs by mapping input symbols to subcarriers included in each of the plurality of sub-blocks, and performing inverse fast Fourier transform (IFFT) on the Alamouti code symbol pairs. Therefore, inter-subcarrier interferences due to frequency error between transmit antennas of a distributed antenna system or a cooperative transmission apparatus may be cancelled in the frequency selective fading channel environment.

Abstract: Disclosed is a method of cancelling inter-subcarrier interferences in distributed antenna system. A method of cancelling interference performed in a transmitting station may include configuring a least one Alamouti pair by mapping subcarrier to each of input symbols, performing a 2N-point inverse fast Fourier transform (IFFT) on the at least one Alamouti pair, wherein the N is a natural number, and performing a frequency up converting on signals on which the 2N-point IFFT performed. Therefore, the inter-subcarrier interferences can be canceled efficiently.

Abstract: Provided are a safety earphone system and a method of driving the same. The safe earphone system includes a microphone block that includes: a sound input terminal for receiving sound information from a sound system; a sound output terminal for receiving the sound information and transmitting the sound information to an earphone; a microphone unit for detecting an outside sound; and a controller for decreasing the sound information volume or blocking a connection between the sound output terminal and the sound input terminal if a level of the outside sound detected by the microphone unit exceeds a threshold value. Accordingly, an output state of the earphone is adjusted according to a level of the outside sound detected by a microphone module. In other words, a user may hear the outside sound while wearing the earphone since the sound information transmitted to the earphone is blocked if the level of the outside sound exceeds the threshold value.

Abstract: Provided is an iterative residual frequency and phase compensation apparatus for an OFDM system and a method thereof. The apparatus includes: a first classifying unit for classifying symbol sequences by each subcarrier wave; a soft-decision calculating unit for calculating a soft-decision value of a data symbol using a soft-decision reliability obtained from iterative decoding performed by the iterative decoder; a classifying unit for classifying the soft-decision values by a carrier wave; a frequency estimating unit for estimating a residual frequency error of each carrier wave using the soft-decision value; a phase estimating unit for estimating an average residual phase error using the soft-decision value; a frequency and phase compensating unit for compensating frequencies and phases for input symbols of each carrier wave using the estimated frequency error and the estimated phase error; and a buffer for temporally storing the compensated symbols to provide it to the first classifying unit.

Abstract: Provided is an iterative residual frequency and phase compensation apparatus for an OFDM system and a method thereof. The apparatus includes: a first classifying unit for classifying symbol sequences by each subcarrier wave; a soft-decision calculating unit for calculating a soft-decision value of a data symbol using a soft-decision reliability obtained from iterative decoding performed by the iterative decoder; a classifying unit for classifying the soft-decision values by a carrier wave; a frequency estimating unit for estimating a residual frequency error of each carrier wave using the soft-decision value; a phase estimating unit for estimating an average residual phase error using the soft-decision value; a frequency and phase compensating unit for compensating frequencies and phases for input symbols of each carrier wave using the estimated frequency error and the estimated phase error; and a buffer for temporally storing the compensated symbols to provide it to the first classifying unit.

Abstract: Disclosed is an MC-CDMA scrambling system and method, and a recording medium for storing a program thereof. A transmitter receives user's bit streams, uses a fixed scrambling code, determined according to the user's orthogonal code combinations or the number of users and having a length equal to the number of subcarriers, and generates and outputs multicarrier signals. A receiver uses the scrambling code equal to that used by the transmitter, and receives the multicarrier signals from the transmitter, thereby converting the scrambling codes according to the users' orthogonal code combinations irrespective of user data, and easily reducing the PAPR (peak-to-average power ratio).

Abstract: Provided are multi-carrier (MC)/multi-carrier direct sequence (MC-DS) dual-mode adaptable CDMA apparatus, the method thereof, and a computer program that implements the method. The apparatus can vary the user modulation degree and the transmission repetition degree independently, and convert a spreading scheme between the time-based spreading scheme (MC-DS-CDMA) and the frequency-based spreading scheme (MC-CDMA) in a MC-CDMA system. The apparatus includes: a user signal processing unit for performing symbol modulation, repetition and spreading of bit stream for each user based on a transmission mode suitable for channel environment of each user, and generating spread chip streams for the user; a combining unit for adding up all the spread chip streams for the users; a first interleaving unit for interleaving the chip streams added up in the combining unit and generating a first interleaved stream; and a second interleaving unit for optionally performing a second interleaving on the first interleaved stream.

Abstract: Apparatus and method for closed-loop power control in mobile satellite communication system, which can compensate round trip delay. The apparatus for closed-loop power control includes the means of; a) converting power control order from base earth station into power control step; b) measuring channel change rate from power of pilot channel; c) making tab coefficient using said channel change rate; d) compensating channel change due to loop delay using power control step; and e) renovating received signal power using said power control step.

Abstract: Disclosed is a method for using a different symbol timing for users so as to reduce a multiple access interference component in a multi-carrier code division multiple access (MC-CDMA) system. For this purpose, the presented invention involves dividing the users of the MC-CDMA system into two groups and applying an offset to the symbol timing between the user groups to cause a symbol transition of the opposite user group in the middle of the symbol interval, thereby reducing the multiple access interference component included in a symbol decision variable after a chip combination.

Abstract: Apparatus and method for closed-loop power control in mobile satellite communication system, which can compensate round trip delay. The apparatus for closed-loop power control includes the means of; a) converting power control order from base earth station into power control step; b) measuring channel change rate from power of pilot channel; c) making tab coefficient using said channel change rate; d) compensating channel change due to loop delay using power control step; and e) renovating received signal power using said power control step.