Electronics and Telecommunications Research Institute

Industry-university Cooperation Foundation Hanyang University

Industry-university Cooperation Foundation Sogang University

Vk Corporation

Deock-Gil Oh

Pan-Soo Kim

Dae-Ig Chang

Ho-Jin Lee

In-Ki Lee

Tae-Hoon Kim

Wonjin Sung

Soo-Young Kim

Seokheon Kang

Ki-Dong Lee

Nae-Soo Kim

Yun-Jeong Song

Eun-A Choi

Kwon-Hue Choi

Deokchang Kang

Xavier Giraud

Byoung-Hak Kim

Ji-Won Jung

Min-Su Shin

Ho-Kyom Kim

Jae-Moung Kim

Jin-Ho Kim

Soon-Ik Jeon

Yong-Ho Lee

Soo Young Kim

Jun Young Heo

Do-Seob Ahn

Seong-Jun Lee

Kwang-Jae Lim

Sang-Kyu Park

Seong-Pal Lee

Won-Jin Sung

Sangtae Kim

Pansoo Kim

Kun-Seok Kang

Young-Wan Kim

Hyun-Ha Hong

Gwang-Ja Jin

Nam-Kyung Lee

Joon-Gyu Ryu

Giovanni E Corazza

Dong-Weon Yoon

Kwang-Min Hyun

Joong-Gon Ryoo

Deok-Chang Kang

Seok-Heon Kang

Man-Kyu Park

Jae-Hee Han

Il-Han Kim

Vikas Agarwal

Yun-Jeoug Song

Kun-Nyeong Chang

Ming-Lu Jin

Dae-Ig Jang

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

When errors occur in a packet received from a satellite terminal device, a modulation and coding (MODCOD) value is calculated according to a result of the detection, and a calculated MODCOD value is transmitted to the satellite terminal device, so that packet loss is reduced based on the yield of actual traffic when the satellite terminal device transmits a return link packet. An occurrence of a packet error is detected by generating a first return link packet by sequentially assembling the plurality of return link packets from the satellite terminal device and performing a comparison analysis by comparing the first return link packet with a newly received second return link packet.

Method for detecting return link packet error in hub which communicates with satellite terminal and apparatus thereof

An apparatus and method for producing error correction code and error correction decoding are provided. The method for producing error correction code includes generating an asymmetric matrix by arranging input data bits in a matrix of a predefined size and adding a zero bit column and/or a zero bit row, each of the column and the row consisting of zero bits, to the matrix; primarily encoding the asymmetric matrix by adding one or more parity bits to each row; and secondarily encoding the primarily encoded matrix by adding one or more parity bits to each column of the encoded matrix.

Method of producing and decoding error correction code and apparatus therefor

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 low-density parity-check (LDPC) decoding apparatus and method using a type-classified index. The apparatus includes: a memory allocating unit for multiplying reception data by an estimated channel value and storing a multiplied value in a memory including a plurality of memory block; an index storing unit for storing a Read Only Memory (ROM) index, an address index and a permutation index for the stored data; a check node updating unit for bring the stored data in parallel based on the ROM index, the address index, and the permutation index and updating a check node; and a bit node updating unit for updating a bit node based on the data stored in the memory and check node information updated in the check node updating unit.

LDPC decoding apparatus and method using type-classified index

Provided are an apparatus and method for generating a soft bit metric and a multi-level (M-ary) Quadrature Amplitude Modulation (QAM) receiving system using the same. The apparatus includes an analog to digital converter for converting an analog symbol signal of a demodulated I (Inphase) or Q (Quadrature) channel into a digital signal, a scaler for scaling the converted digital signal based on a reference value used for determining a space between symbols, a positive integer converter for calculating a positive integer of the scaled digital I or Q channel symbol signal, a sign determinator for determining a sign of the scaled digital I or Q channel symbol signal, and a bit information converter for converting the scaled digital I or Q channel symbol signal into soft bit metric information per bit on the basis of the calculated positive integer and the determined sign value.

Apparatus and method for generating soft bit metric and M-ary QAM receiving system using the same

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

There are provided an apparatus and method for traffic performance improvement and traffic security in an interactive satellite communication system. The method for traffic performance improvement of an interactive satellite communication system includes the steps of: a) storing an Internet protocol (IP) packet that is received from a user terminal connected to a satellite mobile terminal of the interactive satellite communication system and is to be transmitted to a central station through a satellite; b) transmitting acknowledgement for the stored IP packet to the user terminal by acting for the central station, before the stored IP packet is transmitted to the central station; and c) transmitting the stored IP packet through the satellite to the central station, and retransmitting an unacknowledged IP packet according to a retransmission request of the central station.

Apparatus and method for traffic performance improvement and traffic security in interactive satellite communication system

Provided are an apparatus for estimating an increment in the number of packets arriving at a transmission queue of each terminal and allocating resources to terminals based on the increment in a Demand Assignment Multiple Access (DAMA) satellite communication system, and a method thereof. The method, includes the steps of: a) comparing a summation of requested time slot quantities of terminals with a total number of available time slots; and b) allocating the time slots as much as the requested time slot quantity to each terminal and allocating remaining time slots additionally in proportion to an estimated increase in the number of packets arriving at a transmission queue of each terminal. The apparatus can raise efficiency of resources allocation in DAMA communications and reduce the packet transmission time in a terminal transmission queue.

Apparatus for allocating resources in DAMA satellite communication system and method thereof

A soft decision demapping method includes defining distance values between a received signal and coordinates of constellation dots, obtaining a difference between a maximum value of distance values when a first bit is 0 and a maximum value of distance values when the first bit is 1, during a soft decision of the first bit of N-bit received signal symbol, acquiring a difference between a maximum value of distance values when a second bit is 0 and a maximum value of distance values when the second bit is 1, during a soft decision of the second bit of the N-bit received signal symbol, and deriving a difference between a maximum value of distance values when an Nth bit is 0 and a maximum value of distance values when the Nth bit is 1, during a soft decision of the Nth bit of the N-bit received signal symbol.

Soft decision demapping method suitable for higher-order modulation for iterative decoder and error correction apparatus using the same

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Daejon, South Korea

Deock-Gil Oh