Abstract: The present disclosure relates to a method for feeding back reliable downlink channel state information from a receiver to a transmitter in a multi-user massive MIMO system based on a reconfigurable intelligent surface, and more particularly, to a method for the receiver to transform acquired downlink channel state information into downlink channel state information in an angle domain and compress the downlink channel state information through a compressed-sensing scheme, and then feed the compressed result back to the transmitter, and for the transmitter to acquire the reliable downlink channel state information through a recovery algorithm. According to the present disclosure, the downlink channel state information is compressed according to a compression and recovery algorithm in an mmWave environment, and only a codeword index suitable for the compressed result is fed back to the transmitter to obtain the effect of reduction in feedback overhead in the entire communication system.

Abstract: The present invention relates to a multi-antenna channel estimation apparatus and method for performing beamforming in a communication system in which only single channel estimation is possible, and relates to a channel estimation apparatus and method for beamforming in which the transmitter generates pilot signals based on the Zadoff-Chu sequence and transmits the generated pilot signals to the receiver, the receiver estimates a channel based on the pilot signal, and feeds back information for beamforming to the transmitter based on the estimated channel information, and it is configured to enable beamforming by converting and setting the signal phase for each antenna according to the feedback received from the transmitter.

Abstract: The present disclosure relates to a method for feeding back reliable downlink channel state information from a receiver to a transmitter in a multi-user massive MIMO system based on a reconfigurable intelligent surface, and more particularly, to a method for the receiver to transform acquired downlink channel state information into downlink channel state information in an angle domain and compress the downlink channel state information through a compressed-sensing scheme, and then feed the compressed result back to the transmitter, and for the transmitter to acquire the reliable downlink channel state information through a recovery algorithm. According to the present disclosure, the downlink channel state information is compressed according to a compression and recovery algorithm in an mmWave environment, and only a codeword index suitable for the compressed result is fed back to the transmitter to obtain the effect of reduction in feedback overhead in the entire communication system.

Abstract: The present inventive concept relates to a method for designing an optimal analog precoder for improving frequency spectrum efficiency in a millimeter wave-based multi-user massive MIMO-based hybrid beamforming system and a hybrid beamforming system applying the same, and more specifically, to a method for designing an optimal analog precoder using an approximation technique and an iterative optimization algorithm, and a hybrid beamforming system to which the same is applied.

Abstract: Provided is a lip-sync video providing apparatus for providing a video in which a voice and lip shapes are synchronized. The lip-sync video providing apparatus is configured to obtain a template video including at least one frame and depicting a target object, obtain a target voice to be used as a voice of the target object, generate a lip image corresponding to the voice for each frame of the template video by using a trained first artificial neural network, and generate lip-sync data including frame identification information of a frame in the template video, the lip image, and position information regarding the lip image in a frame in the template video.

Abstract: The present inventive concept relates to a multi-antenna channel estimation apparatus and method for performing beamforming in a communication system in which only single channel estimation is possible, and relates to a channel estimation apparatus and method for beamforming in which the transmitter generates pilot signals based on the Zadoff-chu sequence and transmits the generated pilot signals to the receiver, the receiver estimates a channel based on the pilot signal, and feeds back information for beamforming to the transmitter based on the estimated channel information, and it is configured to enable beamforming by converting and setting the signal phase for each antenna according to the feedback received from the transmitter.

Abstract: The present inventive concept relates to a method for designing an optimal analog precoder for improving frequency spectrum efficiency in a millimeter wave-based multi-user massive MIMO-based hybrid beamforming system and a hybrid beamforming system applying the same, and more specifically, to a method for designing an optimal analog precoder using an approximation technique and an iterative optimization algorithm, and a hybrid beamforming system to which the same is applied.

Abstract: A method and an apparatus for estimating synchronization of a broadcast signal in a time domain using a synchronization estimation signal through steps of: performing a correlation operation using a correlation window on a plurality of synchronization estimation signals separated to a plurality of paths and outputting a plurality of correlated signals; delaying the plurality of correlated signals to output a plurality of delayed signals; and estimating the synchronization using the plurality of delayed signals are provided.

Abstract: A MIMO-OFDM system for increasing reliability includes a transmission terminal that includes Nt transmission antennas and transmits a MIMO signal through relay terminals, and a reception terminal that receives the MIMO signal from the relay terminal through Nr reception antennas, and the transmission terminal extracts a composite channel coefficient from a composite channel generated by matching a channel between the transmission terminal and the reception terminal with a channel between each of a plurality of the relay terminals and the reception terminal, selects the relay terminal corresponding to the composite channel coefficient having a maximized channel capacity from among the plurality of relay terminals by using the extracted composite channel coefficient, and transmits a MIMO signal to the reception terminal through the selected relay terminal.

Abstract: Disclosed is a MIMO-OFDM-based intercellular cooperative communication system and a cooperative communication method using the system, the system and method using the system mitigate influence of an intercellular interference and to increase reliability of the mobile terminal located at an edge of a cell, using a CoMP scheme by which base stations cooperate in a HetNet system, a pre-coding scheme by which a channel coefficient of a desired signal increases and a channel coefficient of an interference signal is reduced, and a MIMO detection scheme with an excellent signal detection performance.

Abstract: A method and an apparatus for estimating synchronization of a broadcast signal in a time domain using a synchronization estimation signal through steps of: performing a correlation operation using a correlation window on a plurality of synchronization estimation signals separated to a plurality of paths and outputting a plurality of correlated signals; delaying the plurality of correlated signals to output a plurality of delayed signals; and estimating the synchronization using the plurality of delayed signals are provided.

Abstract: Disclosed is a MIMO-OFDM-based intercellular cooperative communication system and a cooperative communication method using the system, the system and method using the system mitigate influence of an intercellular interference and to increase reliability of the mobile terminal located at an edge of a cell, using a CoMP scheme by which base stations cooperate in a HetNet system, a pre-coding scheme by which a channel coefficient of a desired signal increases and a channel coefficient of an interference signal is reduced, and a MIMO detection scheme with an excellent signal detection performance.

Abstract: The present invention provides a method and apparatus for transmitting a preamble for multiple channel estimation. The method includes generating a channel estimation sequence, allocating the channel estimation sequence to some of a plurality of symbols in which a preamble is transmitted, and transmitting the preamble. The channel estimation sequence is generated by bisecting a sequence having a length N, generating a first sequence and a second sequence by adding a Zero-padded Suffix (ZS) having a zero value to a last part of each of the two bisected sequences, copying the first sequence and the second sequence at least once, and allocating the first sequences and the second sequences to some of the symbols.

Abstract: The present invention provides a method and apparatus for transmitting a preamble for multiple channel estimation. The method includes generating a channel estimation sequence, allocating the channel estimation sequence to some of a plurality of symbols in which a preamble is transmitted, and transmitting the preamble. The channel estimation sequence is generated by bisecting a sequence having a length N, generating a first sequence and a second sequence by adding a Zero-padded Suffix (ZS) having a zero value to a last part of each of the two bisected sequences, copying the first sequence and the second sequence at least once, and allocating the first sequences and the second sequences to some of the symbols.

Abstract: The diversity techniques—space time block code (STBC), maximum ratio combining (MRC)—with multiple antennas provide better reliability than general system. But there are some limitations such as size, cost, hardware complexity, etc, because of multiple antennas. In this letter, we propose a cooperative transmission technique using STBC. We can overcome those limitations and give the gain of cooperative transmission diversity in a concept of virtual multi-input multi-output (MIMO) with single transmit antenna.

Abstract: A method of adaptive modulation in an OFDM system with channel evaluation with two types of adaptive transmission schemes that include several modulation schemes to achieve efficient transmission service. By evaluating channel environment, the methods select the proper modulation scheme among the BPSK, QPSK, 16QAM, and 64QAM. Therefore, the methods either increase the performance or reduce the signaling overhead. By using the method, the reliable and efficient transmission services are achieved.

Abstract: A method of enhanced detection technique is used with wireless MIMO communication system. Since the performance of V-BLAST system depends on the first sub-stream detection capability, V probable streams are detected according to the first detected sub-stream of DFE detector and most probable stream is selected by likelihood test. The performance of the V-BLAST system can be improved and the decoding complexity and system performance can be controlled by adjusting the number of V.

Abstract: The diversity techniques—space time block code (STBC), maximum ratio combining (MRC)—with multiple antennas provide better reliability than general system. But there are some limitations such as size, cost, hardware complexity, etc, because of multiple antennas. In this letter, we propose a cooperative transmission technique using STBC. We can overcome those limitations and give the gain of cooperative transmission diversity in a concept of virtual multi-input multi-output (MIMO) with single transmit antenna.

Abstract: Disclosed is a method of estimating carrier frequency offset in an OFDM system. The method includes the steps of forming one OFDM symbol which has M repeated identical signal block, being a base sub-block; forming a 2i number of identical ith sub-blocks using an M/2i number of the M number of base sub-blocks as a unit; and estimating an ith carrier frequency offset &egr;i using a correlation between two adjacent ith sub-blocks in the 8i number of the ith sub-blocks.