Abstract: Disclosed are a communication apparatus and a communication method capable of improving transmitting/receiving frequency efficiency of a satellite signal per bandwidth or spectral efficiency (S.E) per bandwidth by removing and improving a distortion or inter-symbol interference for applying a minimum-mean square error (MMSE) equalizer required to detect a frame synchronization and a modulation code rate in a satellite service for satellite broadcasting or communication under the variable coding and modulation (VCM) or adaptive coding and modulation (ACM) environment.

Abstract: Disclosed are a signal receiving apparatus based on FTN and a signal decoding method thereof, and the apparatus includes: an equalizer calculating, when a signal sampled by Fast to Nyquist (FTN) is received on a communication channel, a posterior probability of information bits and calculating a log likelihood ratio by using the calculated posterior probability; a deinterleaver deinterleaving bit data output from the equalizer; a decoder correcting of signal interference of the data bits deinterleaved by the deinterleaver by using the LLR and decoding the corrected signal interference; and an interleaver interleaving data output from the decoder to provide the interleaved data to the equalizer.

Abstract: Disclosed is a broadcasting transmission apparatus for simulcast broadcasting, including: a first stream generating unit configured to generate a first video stream by encoding video data; a second stream generating unit configured to generate a second video stream by encoding the video data; a PMT generating unit configured to generate a program map table (PMT) including a first descriptor that describes whether one or more programs included in the first video stream and the second video stream each are simulcast broadcasting targets and a second descriptor that describes video qualities of the one or more programs; a multiplexing unit configured to generate a first multiplexed stream and a second multiplexed stream by multiplexing each of the first stream and the second stream, and the PMT; a modulation unit configured to modulate the first multiplexed stream and the second multiplexed stream; and a transmission unit configured to transmit the modulated first and second multiplexed streams.

Abstract: Provided is a method of identifying a transmission control protocol (TCP) packet loss, including transmitting at least one TCP data packet to a TCP receiver, estimating wireless channel status information using the TCP receiver by interaction between a TCP layer and a physical layer, and receiving an acknowledgement (ACK) packet including the estimated wireless channel status information from the TCP receiver.

Abstract: A first terminal according to the present invention is a first terminal among a plurality of terminals which is connected to a district center network management device in a VSAT (very small aperture terminal) system, including: a communication unit which connects the first terminal to the district center network management device through a star network; and a control unit which creates SCPC call establishment request information, transmits the created SCPC call establishment request information to the district center network management device through the communication unit, and performs SCPC connection with another terminal based on SCPC call establishment information which is transmitted from the district center network management device in response to the transmitted SCPC call establishment request information when SCPC (single channel per carrier) connection is desired to be performed with another terminal among the plurality of terminals.

Abstract: Provided is a system and method for synchronization between digital-to-analog converters (DAC) for high speed signal processing. A synchronization method of a multi-DAC apparatus may include: inputting a clock to a multiplexer (MUX) DAC; dividing the clock into a first clock and a second clock; transferring a phase difference between the first clock and the second clock to a D flip-flop; and synchronizing the first clock and the second clock by processing the phase difference.

Abstract: A control method of a satellite communication network controller is provided. The satellite communication network controller registers terminals included in a plurality of satellite communication networks. The satellite communication network controller receives first data transmitted by a first terminal from a first central station included in a first satellite communication network. The satellite communication network controller searches from the terminals, a second terminal which is a destination of the first data. The satellite communication network controller determines a second central station to receive the first data by using registered information of the second terminal. The satellite communication network controller transmits the first data to the second central station. The second central station is included in the second satellite communication network.

Abstract: Provided are a satellite mesh communication system and an adaptive coding modulation (ACM) control method using the same. The ACM control method include establishing, by the central station, star and mesh connections between the terminal stations, receiving, by each terminal station, a data burst including MODCOD information for ACM control through the established mesh connection, checking, by each terminal station, a mesh connection link state in response to reception of the data burst, determining, by each terminal station, new requested MODCOD information in units of established mesh connections to transmit a data burst including the determined requested MODCOD information to a partner terminal station, and changing a previous MODCOD according to the requested MODCOD to transmit a data burst in units of mesh connections according to the changed MODCOD.

Abstract: An adaptive coding and modulation (ACM) apparatus and method for a forward link in satellite communication is provided. The ACM apparatus may include a receiving unit to receive a signal-to-noise ratio (SNR) of a received signal, a determination unit to determine whether the SNR of the received signal is less than or equal to a threshold value, and a processing unit to execute a channel prediction algorithm when the SNR of the received signal is determined to be less than or equal to the threshold value.

Abstract: Provided are a modulation method and a demodulation method for satellite communication using a widespread signal-to-noise ratio (SNR), the method including: adding a dummy frame to a broadcasting/communication signal frame for signal transmission of a digital video broadcasting-satellite second generation (DVB-S2) modulator; verifying a spreading factor; adding the same physical layer header to the broadcasting/communication signal frame to which the dummy frame is added, repeatedly the number of times corresponding to the verified spreading factor; and repeating the same data, for example, PL frame data as the physical layer header.

Abstract: Provided is a digital video broadcasting-satellite-second generation (DVB-S2) based transmission and reception apparatus and method operable in circumstances of a low signal to noise ratio (SNR), the DVB-S2 based transmission and reception apparatus including a DVB-S2 based transmitter, a mapping unit to determine bit mapping based on at least one of a state of a transmission channel and an area to be applied, and a physical layer frame (PLframe) replica processing unit to repeat a PLframe in which a physical layer header (PLheader) corresponding to a spreading factor (SF) is inserted.

Abstract: A data transmission and reception apparatus is used for a high efficiency satellite transmission. The apparatus includes an initial phase calculation unit to calculate initial phase information using a preamble and a postamble of a data packet applied thereto, a symbol transition calculation unit to perform forward and backward metric operations using the initial phase information calculated by the initial phase calculation unit and a pilot symbol in the data packet to calculate a symbol transition of the data packet, and a phase error estimation unit to calculating a phase error using the pilot symbol in a spot where the pilot symbol is positioned, the calculated phase error being provided to the symbol transition calculation unit.

Abstract: Provided is a system and method for synchronization between digital-to-analog converters (DAC) for high speed signal processing. A synchronization method of a multi-DAC apparatus may include: inputting a clock to a multiplexer (MUX) DAC; dividing the clock into a first clock and a second clock; transferring a phase difference between the first clock and the second clock to a D flip-flop; and synchronizing the first clock and the second clock by processing the phase difference.

Abstract: An apparatus and method for transmitting, through multiplexing a data frame that generates at least one super frame including at least one slice configured in a unit of a plurality of PLframes, generates a multiplexing super frame by rotating the at least one super frame by a predetermined phase value, and transmits the at least one super frame is provided.

Abstract: Provided is an apparatus and method for iteratively detecting and decoding a received signal in a wireless communication system. An apparatus for iterative detection and decoding (IDD) in a wireless communication system may determine a predetermined group to be updated in a first soft decision sequence, may transmit detection control information of the determined group, and may generate a second soft decision sequence based on a detection operation result of a predetermined received signal portion that is extracted based on the detection control information.

Abstract: Provided are an adaptive coding modulation (ACM)-based simulcast transmission and reception apparatus and method. The apparatus includes a transmitter configured to analyze whether or not it is raining in a region where a receiver is present on the basis of channel state information (CSI) provided by the receiver, encode and/or modulate an image signal according to the analysis result, and provide the encoded and/or modulated image signal through a single band or multiple bands. On the basis of a result of analyzing whether or not it is raining in a region where a receiver is present, it is possible to effectively prevent signal attenuation caused by rain by providing image signals having different resolutions through multiple bands when the region is in a rainfall state.

Abstract: Provided is a multilevel satellite broadcasting system for providing a hierarchical satellite broadcasting, including a demodulator to demodulate a transmitted multilevel compression stream based on a modulation parameter, a hierarchical video decoder to receive the demodulated multilevel compression stream, and a channel predicting and controlling unit to process at least one of channel prediction and channel control with respect to the demodulated multilevel compression stream based on channel information of the demodulator.

Abstract: Provided is a maximum a posteriori (MAP) decoder having a low latency and an operation method of the MAP decoder, including a branch metric calculation block to calculate a branch metric based on a received signal, a processor control block to demultiplex a received signal in a certain trellis section, an Extrinsec vector, and the calculated branch metric value, and a processor to calculate a path metric entering each state node in a certain trellis section, compensate for the calculated path metric, and calculate a state metric to be applied to a next trellis section based on the compensated path metric.

Abstract: Provided is a satellite broadcasting and communication transmitting apparatus and method for a broadband satellite broadcasting and communication service, including a forward error correction (FEC) encoder to generate an FEC frame, a bit mapping framer to perform bit mapping on the generated FEC frame, and a predistorter to predistort the bit mapped frame.

Abstract: A maximum a posteriori (MAP) decoding apparatus and method are provided, which select a path having a maximum value without calculating all path metrics by generating metric difference vectors based on generated tables, calculating metrics of a path formed through a combination of a state and a branch each having a maximum metric, and calculating an index and a metric of a current state to which a calculation value is to be applied based on a result of comparing a state metric difference vector and a branch metric difference vector.