Abstract: Disclosed herein are a synchronization apparatus and method for a upstream system. The synchronization apparatus for a upstream system includes one or more processors, and execution memory for storing at least one program that is executed by the one or more processors, wherein the at least one program is configured to receive a signal and calculate a first channel estimation value for the received signal using a predefined pilot, and calculate a second channel estimation value using a predefined complementary pilot and the first channel estimation value.

Abstract: Disclosed herein are an apparatus and method for detecting a broadcast signal. The apparatus includes a bootstrap detection unit for detecting whether a bootstrap signal is included in a received broadcast signal based on a preset first bootstrap window and a machine-learning method, a bootstrap offset estimation unit for searching the broadcast signal for the start point of the bootstrap signal using a preset second bootstrap window, estimating a bootstrap offset based on the machine-learning method, and estimating bootstrap symbols from the bootstrap offset, and a demodulation unit for demodulating information included in the broadcast signal from the bootstrap symbols based on the machine-learning method.

Abstract: Disclosed herein is a demodulation method of a Layer-Division Multiplexing (LDM) system. The demodulation method may include receiving an LDM modulation signal, restoring a first-layer signal from the LDM modulation signal and remodulating the first-layer signal, restoring and remodulating a second-layer signal by performing cancellation of the amplitude component of the first-layer signal from the LDM modulation signal using signaling information independently of restoration and remodulation of the first-layer signal, and restoring a third-layer signal using the first-layer signal, the second-layer signal, and the LDM modulation signal.

Abstract: Disclosed herein is a demodulation method of a Layer-Division Multiplexing (LDM) system. The demodulation method may include receiving an LDM modulation signal, restoring a first-layer signal from the LDM modulation signal and remodulating the first-layer signal, restoring and remodulating a second-layer signal by performing cancellation of the amplitude component of the first-layer signal from the LDM modulation signal using signaling information independently of restoration and remodulation of the first-layer signal, and restoring a third-layer signal using the first-layer signal, the second-layer signal, and the LDM modulation signal.

Abstract: Disclosed herein is a method of operating an apparatus for providing a cell broadcast service. The operating method includes receiving, by a transmission device of a broadcaster, a cell broadcast service signal containing an emergency alert from a mobile carrier; converting, by the transmission device, the cell broadcast service signal into a public warning broadcast signal; and transmitting, by the transmission device, the public warning broadcast signal to a mobile switching center or a base station.

Abstract: Disclosed are a roll-off period detection method, a symbol starting point detection method, a fractional frequency offset estimating method, and an OFDM downstream system using the same. A method of detecting a roll-off period in an OFDM downstream system according to an embodiment of the present disclosure may include: generating a temporary roll-off period by applying a windowing function to a signal having a preset length; and detecting a roll-off period based on any one of a cross correlation and a sum of differences between a detection target signal included in a range of two OFDM symbol signals based on a detection starting point, and the temporary roll-off period.

Abstract: Disclosed herein are a method for providing an ad-hoc broadcast service based on channel sharing and an apparatus for the same. The method is configured such that a master broadcast transmitter for providing an ad-hoc broadcast service receives a request to share a channel from a new broadcast transmitter, allocates one of multiple subframes, into which the transmission frame of any one broadcast channel corresponding to the ad-hoc broadcast service is divided, to the new broadcast transmitter, and controls the new broadcast transmitter in real time by performing synchronization with the new broadcast transmitter based on reference time information included in a control Physical Layer Pipe (PLP).

Abstract: Disclosed herein are a signal-multiplexing apparatus and method based on machine learning. The signal-multiplexing method based on machine learning, performed by a signal-multiplexing apparatus based on machine learning, including training a transmitted signal using a machine-learning technique, performing complex mapping to transmit the transmitted signal as multiple signals, receiving the multiple signals and regularizing the multiple signals based on a preset rule corresponding to the machine-learning technique, outputting an estimated value for the transmitted signal by training regularized multiple signals using the machine-learning technique, calculating a difference between the transmitted signal and the estimated value for the transmitted signal, and detecting the transmitted signal from an output value when the difference is less than or equal to a preset value.

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: An apparatus and a method for converting an upstream radio frequency (RF) signal to a digital signal and transmitting the digital signal via an Internet protocol (IP) packet based on an optical network in a cable broadcasting network is provided. The apparatus for transmitting an upstream RF signal includes a detector configured to detect an upstream RF signal, and a transmitter configured to digitize the detected upstream RF signal and transmit the digitized RF signal to a headend via an IP packet.

Abstract: Disclosed herein are an apparatus and method for providing a broadcasting service. The method for providing a broadcasting service is performed using a broadcasting service provision apparatus and a terminal device, and includes performing, by the broadcasting service provision apparatus and the terminal device, initialization using information acquired from a downstream signal received from a Cable Modem Termination System (CMTS), converting, by the terminal device, an upstream signal received from a Cable Modem (CM) into a digital signal, encapsulating the digital signal into an IP packet, and transmitting the IP packet to the broadcasting service provision apparatus, and extracting, by the broadcasting service provision apparatus, the digital signal from the IP packet received from the terminal device, converting the digital signal into an analog signal, and transmitting an upstream signal corresponding to the analog signal to the CMTS.

Abstract: Disclosed herein are a method for providing an ad-hoc broadcast service based on channel sharing and an apparatus for the same. The method is configured such that a master broadcast transmitter for providing an ad-hoc broadcast service receives a request to share a channel from a new broadcast transmitter, allocates one of multiple subframes, into which the transmission frame of any one broadcast channel corresponding to the ad-hoc broadcast service is divided, to the new broadcast transmitter, and controls the new broadcast transmitter in real time by performing synchronization with the new broadcast transmitter based on reference time information included in a control Physical Layer Pipe (PLP).

Abstract: Disclosed herein is a synchronization method for transmitting a DOCSIS upstream signal, which is performed by an RoIP terminal, the synchronization method including receiving a synchronization (SYNC) message periodically sent by a Cable Modem Termination System (CMTS) and thereby synchronizing a clock and generating a reference time; receiving a ranging request signal from a Cable Modem (CM); including information about a start time of an allocated ranging interval in the ranging request signal, converting the ranging request signal into an IP packet, and transmitting the IP packet to an RoIP headend device over an IP network in order to enable the RoIP headend device to convert the ranging request signal, delivered via the IP network, into an RF signal and transmit the RF signal to the CMTS; and converting a ranging response message delivered from the CMTS into an electric signal and transmitting the electric signal to the CM.

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 are a roll-off period detection method, a symbol starting point detection method, a fractional frequency offset estimating method, and an OFDM downstream system using the same. A method of detecting a roll-off period in an OFDM downstream system according to an embodiment of the present disclosure may include: generating a temporary roll-off period by applying a windowing function to a signal having a preset length; and detecting a roll-off period based on any one of a cross correlation and a sum of differences between a detection target signal included in a range of two OFDM symbol signals based on a detection starting point, and the temporary roll-off period.

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 herein is a synchronization method for transmitting a DOCSIS upstream signal, which is performed by an RoIP terminal, the synchronization method including receiving a synchronization (SYNC) message periodically sent by a Cable Modem Termination System (CMTS) and thereby synchronizing a clock and generating a reference time; receiving a ranging request signal from a Cable Modem (CM); including information about a start time of an allocated ranging interval in the ranging request signal, converting the ranging request signal into an IP packet, and transmitting the IP packet to an RoIP headend device over an IP network in order to enable the RoIP headend device to convert the ranging request signal, delivered via the IP network, into an RF signal and transmit the RF signal to the CMTS; and converting a ranging response message delivered from the CMTS into an electric signal and transmitting the electric signal to the CM.

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 an apparatus and a method for soft-decision demodulating in non-square quadrature amplitude modulation. The apparatus includes: a signal receiving unit receiving a quadrature amplitude modulation (QAM) modulated signal at an m modulation degree at a transmitting side; a soft-decision bit calculating unit determining a soft-decision bit value by calculating log likelihood ratios (LLRs) for m bits of the received QAM modulated signal; and a signal decoding unit restoring the received QAM modulated signal based on the determined soft-decision bit value, in which the soft-decision bit calculating unit defines a log likelihood ratio calculation equation by approximating soft-decision boundary points of constellation points for m bits of non-square QAM having odd bits, respectively.