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 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 herein are an apparatus and method for detecting an upstream RF signal based on a preamble. The apparatus for detecting an upstream RF signal based on a preamble includes an analog-to-digital converter unit for receiving an RF analog signal and converting the same into an RF digital signal; a down-converter unit for converting the RF digital signal into a baseband digital signal; a packet detection unit for performing packet detection by performing an operation on the baseband digital signal and preset differential preamble signals; and a timing calculation unit for generating timing information of a terminal device based on the baseband digital signal and time information generated through the packet detection.

Abstract: Disclosed are a method for acquiring synchronization in a cable network, and a physical (PHY) transmitter and PHY receiver. The method for acquiring synchronization in a cable network according to an embodiment includes receiving, by a PHY receiver, a signal from a PHY transmitter, and acquiring, by the PHY receiver, channel synchronization when a symbol in which a channel preamble exists is detected from the received signal and a position of a frequency in which a channel subcarrier exists is detected from the detected symbol by performing a cross correlation operation on the received signal and the channel preamble.

Abstract: A method of estimating an integer frequency offset and compensating for the integer frequency offset by an estimated error is provided. A frequency offset estimation method may include receiving a reception signal including PLC data and a physical layer link channel (PLC) preamble, detecting first position information on a position of a subcarrier of the PLC preamble in a frequency axis from the reception signal through a cross-correlation between the PLC preamble and the reception signal, detecting second position information on the position of the subcarrier of the PLC preamble defined in a transmission end by restoring the PLC data, and calculating a frequency offset by comparing the first position information with the second position information.

Abstract: Disclosed herein are an apparatus and method for detecting an upstream RF signal based on a preamble. The apparatus for detecting an upstream RF signal based on a preamble includes an analog-to-digital converter unit for receiving an RF analog signal and converting the same into an RF digital signal; a down-converter unit for converting the RF digital signal into a baseband digital signal; a packet detection unit for performing packet detection by performing an operation on the baseband digital signal and preset differential preamble signals; and a timing calculation unit for generating timing information of a terminal device based on the baseband digital signal and time information generated through the packet detection.

Abstract: A method of estimating an integer frequency offset and compensating for the integer frequency offset by an estimated error is provided. A frequency offset estimation method may include receiving a reception signal including PLC data and a physical layer link channel (PLC) preamble, detecting first position information on a position of a subcarrier of the PLC preamble in a frequency axis from the reception signal through a cross-correlation between the PLC preamble and the reception signal, detecting second position information on the position of the subcarrier of the PLC preamble defined in a transmission end by restoring the PLC data, and calculating a frequency offset by comparing the first position information with the second position information.

Abstract: Disclosed are a method for acquiring synchronization in a cable network, and a physical (PHY) transmitter and PHY receiver. The method for acquiring synchronization in a cable network according to an embodiment includes receiving, by a PHY receiver, a signal from a PHY transmitter, and acquiring, by the PHY receiver, channel synchronization when a symbol in which a channel preamble exists is detected from the received signal and a position of a frequency in which a channel subcarrier exists is detected from the detected symbol by performing a cross correlation operation on the received signal and the channel preamble.

Abstract: Disclosed is a an apparatus for reducing a reducing a peak to average power ratio (PAPR) for layer division multiplexing (LDM) in an orthogonal frequency division multiplexing (OFDM) system, the apparatus may include a peak remover configured to detect a peak power value of a subcarrier signal that is input and generate a peak removal signal that decreases the detected peak power value, and a processor configured to perform constellation remapping on a first signal generated by combining the subcarrier signal and the peak removal signal and then generate a second signal into which additional data is inserted.

Abstract: An apparatus and a method of channel estimation and equalization based on pilot signals, which acquire a channel estimation vector and effectively perform channel equalization by using scattered pilots and continuous pilots in a communication system to which an OFDM symbol is applied, such as a DOCSIS 3.1 Down stream PHY system using multiple carriers.

Abstract: Disclosed are a method and apparatus for estimating symbol timing in a non-synchronized OFDM system. The present invention includes synchronizing a frame of a received signal, estimating the symbol timing of each symbol of the frame based on the synchronization, compensating for the symbol timing using a phase difference attributable to a Symbol Timing Offset (STO), variably changing within a Cyclic Prefix (CP) interval due to the frequency offset of a sampling clock and thermal noise, and performing channel equalization using a preamble based on output including corrected phase rotation.

Abstract: In an orthogonal frequency division multiplexing (OFDM) wireless communication system, when path delay information is received from a reception apparatus through a return path after data transmission, a length of a cyclic prefix included in a transmitted signal is adjusted on the basis of a delay value included in the path delay information.

Abstract: In an orthogonal frequency division multiplexing (OFDM) wireless communication system, when path delay information is received from a reception apparatus through a return path after data transmission, a length of a cyclic prefix included in a transmitted signal is adjusted on the basis of a delay value included in the path delay information.

Abstract: A broadcasting transmitting apparatus splits a piece of broadcast content into an audio signal and a video signal, encodes the audio signal to generate an audio bit string, encodes the video signal to generate a video bit string, multiplexes the audio bit string and the video bit string, and modulates the multiplexed bit strings into a symbol. The encoded audio bit string is allocated to some bits of the symbol, and the encoded audio bit string is allocated to the remaining bits of the symbol.

Abstract: An apparatus for combining a broadcasting channel may include a channel detector to detect a vacant Radio Frequency (RF) broadcasting channel used by a photoelectric converter that converts a first broadcast program as an optical signal to a first RF signal, a broadcast receiving interface to receive at least one second broadcast program, a broadcast modulator to generate a second RF signal by modulating the second broadcast program using the vacant RF broadcasting channel, and a channel combiner to combine a broadcasting channel used for the first RF signal and the vacant RF broadcasting channel.

Abstract: Disclosed are a method and apparatus for estimating symbol timing in a non-synchronized OFDM system. The present invention includes synchronizing a frame of a received signal, estimating the symbol timing of each symbol of the frame based on the synchronization, compensating for the symbol timing using a phase difference attributable to a Symbol Timing Offset (STO), variably changing within a Cyclic Prefix (CP) interval due to the frequency offset of a sampling clock and thermal noise, and performing channel equalization using a preamble based on output including corrected phase rotation.

Abstract: An apparatus for combining a broadcasting channel may include a channel detector to detect a vacant Radio Frequency (RF) broadcasting channel used by a photoelectric converter that converts a first broadcast program as an optical signal to a first RF signal, a broadcast receiving interface to receive at least one second broadcast program, a broadcast modulator to generate a second RF signal by modulating the second broadcast program using the vacant RF broadcasting channel, and a channel combiner to combine a broadcasting channel used for the first RF signal and the vacant RF broadcasting channel.

Abstract: Provided is an automatic gain controlling device that may prevent deterioration in performance of an orthogonal frequency division multiplexing (OFDM) receiver, on a cable network that performs communication by an orthogonal frequency division multiplexing (OFDM) scheme using high-order quadrature amplitude modulation (QAM), the automatic gain controlling device including a power computing unit to compute a power of a signal received by the OFDM receiver, and a gain controller to control a gain of the received signal based on the computed power of the received signal.

Abstract: An Internet Protocol Television (IPTV) Set-Top Box (STB) is provided to efficiently use a time gap caused by a channel switching. The IPTV STB may request a network switch to perform a channel switching operation so that a national service broadcast stream of a second channel is received, when a channel selection signal for the second channel is received while a national service broadcast stream of a first channel is received. Additionally, the IPTV STB may transmit a local service broadcast stream received from a broadcast stream receiver to a display device.

Abstract: Provided is an automatic gain control (AGC) apparatus of a cable modem. The apparatus includes: a gain controller for measuring a power level of digital input signals transmitted from outside, accumulating the measured values of the digital input signals for a predetermined period, acquiring an average size of the signals, and calculating an error value between the average signal size and a predetermined signal size; an amplitude control unit for receiving error values adjusted by the gain controller and controlling an amplitude of the signal; a low pass filter for receiving the signal outputted from the amplitude control unit and performing low pass filtering on the signal; and a signal size control unit for receiving the signal obtained from filtering of the low pass filter and controlling the signal size.