Electronics and Telecommunications Research Institute

Industry-university Cooperation Foundation Sogang University

Industry-university Cooperation Foundation Hanyang University

Dae-Ig Chang

Deock-Gil Oh

Pan-Soo Kim

In-Ki Lee

Tae-Hoon Kim

Wonjin Sung

Seokheon Kang

Ho-Jin Lee

Pansoo Kim

Deokchang Kang

Nae-Soo Kim

Sangtae Kim

Dong-Weon Yoon

Jin-Young Kim

Jae-sung Park

Seong-Jun Lee

Sang-Kyu Park

Won-Jin Sung

Eun-A Choi

Hyun-Ha Hong

Namshik Kim

Joon-Gyu Ryu

Giovanni E Corazza

Ki-seop Han

Cheon-In Oh

Habong Jung

Kijoon Lee

Euna Choi

Kwang-Min Hyun

Bongseop Song

Hyuncheol Park

Deok-Chang Kang

Seok-Heon Kang

Seung-Hyun Choi

Young-Sun Lim

Raffaella Pedone

Marco Villanti

A phase locked loop includes: a loop filter; a voltage controlled oscillating unit configured to output a frequency varying according to an output voltage of the loop filter; a frequency down-converting unit configured to down-convert an output frequency of the voltage controlled oscillating unit according to a band of the output frequency of the voltage controlled oscillating unit; and a frequency divider configured to divide a frequency down-converted by the frequency down-converting unit. The output frequency of the voltage controlled oscillating unit varies according to the output voltage of the loop filter and a control signal compensating the frequency down-converted by the frequency down-converting unit.

Phase locked loop and satellite communication terminal using the same

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 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

Provided is a decoding apparatus and method based on a variable error correction value. The decoding method includes setting an initial normalized factor and a normalized factor correction value, initially updating a check node based on the initial normalized factor, and updating the check node based on a variable error correction value acquired by adding the initial normalized factor and the normalized factor correction value.

Decoding apparatus and method based on variable error correction value

Provided is a method for handover between heterogeneous networks using a link trigger signal in a multi-interface mobile router. The method includes: maintaining a state of a second network access interface in a sleep state, activating a first network access interface, receiving and transmitting the first network service to a subordinate node in the mobile router located in a first network; when the mobile router senses a second network link-up trigger signal while moving to the second network, changing the state of the second network access interface into an active state and performing handover; and receiving a second network service through the activated second network access interface in the mobile router performing the handover and transmitting the second network service to the subordinate node.

Method for handover between heterogeneous networks using link trigger signal in multi-interface mobile router

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 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 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 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

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

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 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.

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Daejon, South Korea

Dae-Ig Chang