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 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 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:
Disclosed is a star network/mesh network accessing method and apparatus of a terminal in a satellite communication system, the method including receiving time slot resources from a central station and operating in a time division multiple access (TDMA) start network communication mode between the central station and a terminal, transferring, to the central station, a TDMA mesh network connection request message for a destination terminal, receiving traffic burst time plan (TBTP) information corresponding to the TDMA mesh network connection request message from the central station and operating in a TDMA mesh network communication mode between terminals, and switching from the TDMA mesh network communication mode between the terminals to a single channel per carrier (SCPC) mesh network communication mode between the terminals when Voice over Internet Protocol (VoIP) traffic is greater than a threshold.
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 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:
Disclosed is a communication method performed between a satellite and a ground station and apparatuses performing the communication method. The communication method includes transmitting a plurality of frames based on a beam allocation time schedule (BATS) between a satellite and a ground station, and synchronizing the BATS based on a reception time and a detection time of one or more frames among the plurality of frames to be received through a beam open window (BOW) allocated to the ground station.
Abstract:
A signal processing method, and a transmitter and a receiver are disclosed. The signal processing method may include converting a transmission signal to a non-periodic sequence type transmission signal using periodic sequences and transmitting the non-periodic sequence type transmission signal to the receiver, in which the receiver may detect a burst from the received non-periodic sequence type transmission signal.
Abstract:
Disclosed is a network synchronization apparatus and method of a time division multiple access (TDMA)-based mesh network satellite communication system, the network synchronization method of a terminal in a satellite communication system including receiving timing error information from a central station, generating a mesh superframe start time (SST′) by reversing a sign of the timing error information, and receiving traffic information transmitted by a transmission terminal using the mesh SST′.
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.