Electronics and Telecommunications Research Institute

Industry-University Cooperation Foundation Hanyang University

Industry-university Cooperation Foundation Sogang University

Pan-Soo Kim

Deock-Gil Oh

Dae-Ig Chang

Tae-Hoon Kim

Wonjin Sung

Seokheon Kang

Ho-Jin Lee

In-Ki Lee

Deokchang Kang

Xavier Giraud

Byoung-Hak Kim

Jun Young Heo

Seong-Jun Lee

Won-Jin Sung

Sangtae Kim

Yun-Jeong Song

Giovanni E Corazza

Cheon-In Oh

Dae-Ig Jang

Yun-Jeoug Song

Seung-Hyun Choi

Seok-Heon Kang

Deok-Chang Kang

Joong-Gon Ryoo

Vikas Agarwal

Jae-Hee Han

Raffaella Pedone

Marco Villanti

A communication apparatus for a continuous phase modulation signal. The communication apparatus includes a first processing unit configured to generate first information of the continuous phase modulation signal using first symbol data; a symbol converting unit configured to convert the first symbol data into second symbol data or convert the second symbol data into the first symbol data; a symbol storage unit configured to store the second symbol data; a second processing unit configured to second information of the continuous phase modulation signal using the second symbol data stored in the symbol storage unit; a third processing unit configured to generate third information of the continuous phase modulation signal using a modulo operation of an integer related to a modulation index; and an output unit configured to add an output from the third processing unit and an output from the first processing unit and generate the continuous phase modulation signal.

Communication apparatus for continuous phase modulation signal

A technology for modulating and demodulating a burst signal in a return link of a satellite system, in which the burst signal is modulated and transmitted from a transmission end of the return link and a symbol of the burst signal is identified and demodulated at a receiving end. The method includes estimating symbol timing of a burst received through the return link and synchronizing the estimated symbol timing of the burst to reference symbol timing; synchronizing a location of the timing-synchronized burst having the symbol timing synchronized to a location of a reference burst using a preamble symbol and a post-amble symbol of the timing-synchronized burst; and recovering a carrier of the location-synchronized burst whose location has been synchronized to the location of the reference burst using a pilot symbol of the location-synchronized burst.

Signal demodulation method and apparatus and signal modulation method and apparatus in return link of satellite system

Provided is a frame synchronization apparatus capable of reducing the amount of total computation and computation delays when a receiver of a satellite communication system calculates correlation between an input signal for frame synchronization and a signal sequence of the receiver, since the receiver uses no multiplier. The frame synchronization apparatus includes a correlator to obtain a correlation value of a unique word of a receiver with respect to a symbol data stream of a frame received from a transmitter of the satellite communication system, a comparator to compare the correlation value to a predetermined threshold value, and a determiner to determine whether the frame has been synchronized, based on the result of the comparison by the comparator.

Apparatus and method for frame synchronization in satellite communication system

Provided is a method for detecting frame sync and frame structure in a satellite broadcasting system, which acquires an estimated value for detecting frame structure and frame sync and overcomes distortion of correlation analysis values by summing differential correlation values for SOF positions in consideration of the variable frame length, and selecting a maximum value in a channel environment with low signal-to-noise ratio and high frequency error. SOF is a sync word indicating the start point of a frame. The method includes the steps of: acquiring SOF differential correlation value sequences; acquiring sums (d) of the correlation values normalized for SOF positions based on the number of symbols per frame by using the above-generated SOF differential correlation value sequences; and selecting a maximum value (d) among the sums of correlation values, detecting z as a frame sync position, and detecting x as a frame structure index.

Method for detecting frame synchronization and structure in DVB-S2 system

An apparatus and method for acquiring reliable frame synchronization performance and frequency synchronization simultaneously in a communication system includes a differential correlator outputting a result value obtained by performing a differential operation based on an input signal having symbol timing synchronization and a value pre-defined with a sender sending the input signal, a frequency error calculator compensating for a frequency error based on the result value of the differential correlator and a frequency compensation control signal, and a frame synchronization determiner outputting the frequency compensation control signal if the result value of the differential correlator is greater than a threshold set having at least one value. By introducing a correlation scheme, i.e. Differential Generalized Post Detection Integration (DGPDI), in which differential information corresponding to a half of a symbol duration length is used within a duration from a frame start symbol to a UW symbol duration in a TDM/TDMA transmission structure in which a low SNR and a high frequency error must be considered, a more reliable frame synchronization estimation value can be acquired in comparison to a conventional frame synchronization scheme in which differential information between single neighbor symbols is used.

Apparatus and method for acquiring frame synchronization and frequency synchronization simultaneously in communication system

Provided is a method for detecting frame sync and frame structure in a satellite broadcasting system. The method for detecting frame sync and frame structure includes the steps of: calculating differential correlation values of reception symbols; generating index sequences of reception symbols whose differential correlation values calculated above exceed a threshold value; calculating positions estimated as frame start points which correspond to a total frame number based on the number of symbols per frame for each frame structure; and detecting frame sync and frame structure based on the umber of positions where the above-calculated frame start point estimated positions and the above-generated index sequences are matched.

Frame synchronization and structure detection method in DVB-S2 system

Provided are an apparatus for estimating a phase error and a phase error correcting system using the phase error estimating apparatus. The apparatus includes: a probability value estimating unit for estimating a negative log probability value for each transmission symbol by transforming a soft output information transferred from the outside to a log A posterior probability ratio (LAPPR) value; an APP value calculating unit for calculating a posterior probability (APP) value by applying a negative exponential function to the transmission symbol; an average value deciding unit for deciding an average value for each transmission symbol using the probability information entirely, partially, or selectively according to a probability information type; and a symbol phase estimating unit for estimating a phase of a symbol based on the decided average value.

Apparatus for estimating phase error and phase error correction system using the same

Provided are an apparatus and method for deciding a transmission format using a variable frame length and a decoding method using the same. The apparatus for deciding the transmission format using the variable frame length includes: a frame synchronization acquiring unit for acquiring a frame synchronization of a received transmission frame; a correlation analyzing unit for performing a correlation analysis with respect to the transmission frame whose synchronization is acquired, considering frame lengths of respective frame structures; and a transmission frame structure deciding unit for deciding the structure of the received transmission frame using the analyzed correlation. Accordingly, a physical layer signaling code (PLSC) demodulation and decoding performance can be enhanced by determining the structure of the transmitted frame without carrying out a PLSC decoding in such a state that a frequency synchronization is not acquired.

Apparatus and method for deciding transmission format using variable frame length and decoding method using the same

An apparatus for independently extracting streams from a hierarchically-modulated signal and performing a soft-decision, and a method thereof are provided. The apparatus includes: a synchronizing unit for receiving a hierarchically-modulated signal configured of an I-channel signal and a Q-channel signal from an external device and performing a synchronizing process on the received signal; a divaricating unit 410 for divaricating the synchronized signal configured of the I-channel signal and the Q-channel signal from the synchronizing unit; a high priority (HP) stream extracting and soft-decision unit for extracting a HP stream from one of the divaricated signals, and performing a soft-decision; a processing unit for processing the other of the divaricated signals to allow constellation points to be distinguished; and a low priority (LP) stream extracting and soft-decision unit for extracting a LP stream from the processed signal from the processing unit and performing a soft-decision.

Apparatus for independently extracting streams from hierarchically-modulated signal and performing soft-decision, and method thereof

An apparatus and method for correcting a frequency offset in a satellite digital video broadcasting system includes a frequency response transformer for receiving a satellite digital video broadcasting signal and acquiring frequency responses divided into positive and negative frequency parts; a rotation/difference value calculation unit for selecting a frequency response inputted from the frequency response transformer and calculating a first value indicating a difference in area without rotation for the selected frequency response, and calculating a second value indicating a difference in area with rotation for the remaining frequency responses; a zero intersection point calculator for dividing an average slope of a straight line formed by the first and second values by the first value, and calculating a zero intersection point of an area difference value on the straight line; and a frequency offset estimator for correcting the zero intersection point to thereby estimate the frequency offset.

Apparatus and method for correcting frequency offset in satellite digital video broadcasting system

Provided is a method for estimating carrier wave or doppler frequency offset based on an approximated quadratic non-linear function in fine search, and a receiver employing the method. The method for estimating frequency offset includes the steps of: a) extracting more than three discrete samples in an order where the discrete samples are close to a maximum value of a power spectrum density function; b) inducing a quadratic non-linear function by using the extracted discrete samples; and c) estimating the frequency offset from a maximum point of the quadratic non-linear function. The technology of the present research makes it possible to exactly estimate frequency offset without increasing hardware complexity in estimation of carrier wave or doppler frequency offset.

Frequency offset estimating method and receiver employing the same

Provided is a decoding method for detecting Physical Layer Signaling Codes (PLSCs) from frames of a satellite broadcasting system. The method includes: a) acquiring a summation vector and a subtraction vector from an inputted symbol vector; b) performing parallel Reed-Muller (32,6) decoding onto the summation and subtraction vectors based on a Hadamard matrix and estimating message bits of the summation and subtraction vectors; c) performing PLSC coding and modulation onto the message bits of the summation and subtraction vectors; d) calculating a first difference between symbols of the received symbol vector and the summation vector symbols, and a second difference between the symbols of the received symbol vector and the subtraction vector symbols; and e) when the first difference is smaller than the second difference, determining a Reed-Muller codeword is repeated, or when the first difference is larger than the second difference, determining that the Reed-Muller codeword is inverted.

Decoding method for detecting PLSC from frames of satellite broadcasting system

Provided is a frame synchronization method for synchronizing frames with pilot blocks added thereto based on differential correlation information in a satellite communication system. The method can acquire a highly reliable frame synchronization estimation value by achieving a multi-step threshold value test using pilot blocks after a correlation analysis and a threshold test based on a sync signal in order to resolve the problem of a low signal-to-noise ratio and a large frequency error and acquire highly reliable frame synchronization performance, and can overcome distortion of a correlation analysis value caused by the frequency error by analyzing correlation based on differential information. The method includes the steps of: a) performing correlation analysis and a threshold test by using a sync word; and b) performing a multi-step correlation value test by using the pilot blocks added to the frames prior to the sync word.

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Daejon, South Korea

Pan-Soo Kim