Electronics and Telecommunications Research Institute

Industry-university Cooperation Foundation Sogang University

Pansoo Kim

Deock Gil Oh

Ho-Jin Lee

Dae-Ig Chang

Joon Gyu Ryu

In-Ki Lee

Soo Yeob Jung

Jin-Young Kim

Soon-Ik Jeon

Deock-Gil Oh

Nae-Soo Kim

Jae-sung Park

Wonjin Sung

Sangtae Kim

Yun-Jeong Song

Xavier Giraud

Namshik Kim

Jonggyu Oh

Young-Sun Lim

Bongseop Song

Hyuncheol Park

An ultra-low power data transmission method and apparatus are disclosed. An ultra-low power data transmission method to be performed by a user terminal of an ultra-low power data transmission system includes performing channel coding on a payload included in a transmission packet; interleaving a payload obtained through the channel coding, spreading the interleaved payload using a gold code and an orthogonal variable spreading factor (OVSF), combining a synchronization header spread using the gold code and the OVSF with the spread payload, and modulating a transmission packet in which the payload and the synchronization header are combined.

Ultra-low power data transmission method and apparatus

Disclosed is a communication method of a satellite and a ground station and apparatuses performing the same. The communication method includes transmitting a plurality of frames to a satellite based on a beam hopping time plan (BHTP) of the satellite and a ground station and synchronizing the BHTP based on an index of a frame received through a beam switching window (BSW) allocated to the ground station among the plurality of frames, and an identification value indicating at least one sub-frame included in the frame.

Communication method of satellite and ground station, and apparatuses performing the same

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.

Communication method and apparatuses performing the same

Disclosed is a demodulation method to be used by an apparatus receiving a data packet transmitted in wired and wireless communications to recover data from a received signal. The apparatus receiving the data packet may recover or synchronize a symbol timing that is used to recover the data, and a demodulator included in the apparatus receiving the data packet may determine the symbol timing through different methods based on a length of a burst included in the data packet.

Modem performing modulation or demodulation based on length of burst in data packet, and method performed by the modem

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.

Signal processing method and transmitter and receiver

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.

Data transmission and reception method and apparatus robust against phase noise for high efficiency satellite transmission

Disclosed is a phase error estimating an apparatus and a method which provides improved convergence speed and tracking speed even in mobile channel environment by variably applying the step size for phase error estimation according to channel status. The apparatus for estimating a phase error includes: a posterior probability (APP) average calculating unit for calculating an APP average value from a soft decision result of a currently received symbol; a step size determining unit for determining a step size variably according to channel status; and a phase error estimating unit for estimating a phase error of the currently received symbol from a phase error of a previously received symbol and the APP average value by using the variably determined step size.

Apparatus and method for estimating phase error based on variable step size

Provided is a correlation scheme selecting apparatus and method that can acquire initial synchronization efficiently by calculating frequency error criterion threshold between correlation schemes and selecting a correlation scheme for each region when a correlation value is calculated for initial sync in a communication system with carrier frequency errors. The method for selecting a correlation scheme based on a carrier frequency error includes: calculating mis-detection probability values based on a normalized frequency offset for each correlation scheme; determining as a frequency-error criterion threshold a crossing point of graphs of the calculated mis-detection probability values for each correlation scheme; and selecting a correlation scheme based on the determined frequency-error criterion threshold.

Apparatus and method for selecting correlation scheme based on carrier frequency error

Provided are repetition apparatus and method for repeatedly transmitting and receiving a data packet using different puncturing patterns to overcome signal attenuation and fading in a high speed mobile environment by repeatedly transmitting the duplicated information bit sequences with parity bits having a different puncturing pattern after channel-encoding the duplicated information bit. The repetition apparatus for repeatedly transmitting a data packet, includes a dual data generator for generating duplicated information bit sequences identical to each of information bit sequences to transmit, a channel encoder for dividing each of the duplicated information bit sequences into a plurality of information bits, and generating coded data packets alternately having a plurality of parity bits according to different puncturing patterns for each of the divided information bits, and a transmitter for transmitting the generated coded data packets sequentially.

Repetition apparatus and method for repeatedly transmitting and receiving data packet using different puncturing patterns

Provided are an apparatus for estimating frequency offset from received signal and method for the same. The apparatus and method estimates frequency offset precisely without increment of autocorrelator by performing moving average filtering on a noised signal to thereby alleviate jitter. The frequency offset estimating apparatus includes: moving average filter for alleviating jitter of received signal; multiplier for multiplying a filtered signal by conjugate complex operanded pilot signal; phase-rotation value calculator for calculating a phase-rotation value from multiplicand operanded signal by using of symbol delay and an autocorrelation function; frequency offset estimator for estimating frequency offset from the phase-rotation value based on a smoothing function multiplication.

Apparatus for estimating frequency offset from received signal and method for the same

A quadrature transceiving system for compensating a direct current (CD) offset, a gain imbalance and a phase imbalance between an I-channel signal and a Q-channel in a quadrature transmitting system is disclosed. The quadrature transceiving system includes a transmitter for detecting a DC offset, a gain imbalance and a phase imbalance by using an average of a data aided signals included in a RF transmitting signal and compensating one of the I-channel and the Q-channel based on the detected imbalances and DC offset; and a receiver for detecting a DC offset, a gain imbalance and a phase imbalance by varying loop filter gain and compensating one of the I-channel and the Q-channel based on the detected imbalances and DC offset.

Growing community of inventors

Daejon, South Korea

Pansoo Kim