Abstract:
Provided is a maximum a posteriori (MAP) decoding apparatus and a method which selects a path having a maximum value without calculating all the path metrics by generating metric difference vectors based on generated tables, calculating metrics of a path formed through a combination of a state and a branch each having a maximum metric, and calculating an index and a metric of a current state to which a calculation value is to be applied based on a result of comparing a state metric difference vector and a branch metric difference vector.
Abstract:
The present invention relates to a technique to enable an apparatus to operate in environments of a broad signal to noise ratio in satellite communications and broadcasting service, which may comprise a mapping unit which utilizes a selected constellation to modulate a forward error correction frame; a physical layer header processing unit which adds a physical layer header to the modulated forward error correction frame; a physical layer frame diffusing unit which diffuses a physical layer frame of the modulated forward error correction frame; and a physical layer scrambling unit which scrambles the added physical layer header and the diffused physical layer frame.
Abstract:
Provided are an apparatus and a method for receiving a satellite broadcast. The apparatus for receiving a satellite broadcast predicts a channel by using a received signal-to-noise ratio (SNR) information, determines an image signal to be received, among two or more image signals, according to the predicted channel, and controls to selectively receive the determined image signal.
Abstract:
A method for estimating frequency offset in a digital broadcasting system estimates frequency offset by using start of frame (SOF) symbols forming a header of a received physical layer frame and physical layer signalling code (PLSC) symbols for providing a modulation mode and code rate information. [Reference numerals] (410) Receiving unit; (420) Approximate frequency estimation unit; (430) Decoding unit; (440) Fine frequency estimation unit
Abstract:
PURPOSE: A method for producing and decoding an error correcting code and an apparatus thereof are provided to perform encryption by using an error correcting code in a data transmitting process in a satellite communication system. CONSTITUTION: A asymmetric matrix is generated by adding a column and/or a row consisting of zero bits to a matrix(110). Primary coding is performed by adding parity bits to the row of the asymmetric matrix consisting of data bits and the zero bits(130). Secondary coding is performed by adding the parity bits to each row of the encoded matrix in the primary encoding(150). The column and/or the row of the added zero beat are deleted from an asymmetric matrix generating step in the encoded matrix(170).
Abstract:
PURPOSE: A dual mode network synchronization apparatus of a center station for a satellite communication system and method thereof are provided to operate a satellite communication system regardless of a network synchronization method. CONSTITUTION: A timing creation unit(230) is synchronized with a PPS(Pulse Per Second) signal received from a reference clock creation module. The timing creation unit creates an interrupt signal. An NCR counter(220) extracts NCR values corresponding to a point directed by the interrupt signal. A packet creation unit(240) creates MPEG2-TS(Moving Picture Expert Group 2-Transport Stream) packets. The MPEG2-TS packet includes the NCR value extracted by the interrupt signal.
Abstract:
1. 청구범위에 기재된 발명이 속한 기술분야 본 발명은 저 복잡도 LDPC(Low Density Parity Check)복호 장치 및 그 방법에 관한 것임. 2. 발명이 해결하려고 하는 기술적 과제 본 발명은, 저 복잡도 부분적 그룹을 가진 순차적 복호알고리즘을 LDPC복호알고리즘에 적용함으로써, 기존의 복호 알고리즘과 비교하였을 때, 성능 열화 없이, 계산량 증가없이 반복복호에 필요한 반복의 수는 기존알고리즘이 요구하는 것보다 반 이상의 복호횟수를 절감하도록 저 복잡도 부분적 그룹을 가진 순차적 복호알고리즘을 적용한 LDPC 복호 장치 및 그 방법을 제공하는데 그 목적이 있음. 3. 발명의 해결방법의 요지 본 발명은, 저복잡도 부분적 그룹을 가진 순차적 복호알고리즘을 적용한 LDPC 복호장치에 있어서, 수신된 잡음과 LDPC부호어 데이터들과 관련된 성상도의 심볼들 사이의 거리와 관련한 채널값들 정보에 기초하여 사전확률정보를 수신하는 수신수단; 상기 비트노드를 초기화 하는 비트노드 초기화 부; 상기 사전확률정보에 기초하여 검사노드 정보를 업데이트 하기 전에 검사노드를 n개의 검사노드를 갖는 부분 그룹으로 구분하는 검사노드 그룹화부; 및 상기 구분된 첫번째 부분그룹의 검사 노드를 업데이트 하고, 상기 업데이트된 검사노드를 통해 비트노드를 업데이트 하며, 순차적으로 다른 부분 그룹의 검사노드를 업데이트하되, 소정 반복 횟수 만큼 상기 업데이트를 반복수행한 후 종료하는 반복루프 수행부를 포함함. 4. 발명의 중요한 용도 본 발명은 LDPC부호를 복호하기 위한 복호기등에 이용됨. LDPC, 저밀도 패리티 검사, 반복복호,
Abstract:
A method and an apparatus of acquiring synchronization of a system are provided to decrease an initial synchronization time by performing a frequency synchronization and a frame synchronization at the same time. A synchronization apparatus of a communication system having a frame with a header of a fixed length includes a differential correlator(210), a frequency difference calculator(220), and a frame synchronization determiner(230). The differential correlator performs a differential calculation based on an input signal and a contracted value. A symbol timing is synchronized in the input signal. The contracted value is determined between the differential correlator and a sender. The frequency difference calculator compensates for a frequency error in the input signal based on a result from the differential correlator and a frequency compensation control signal. The frame synchronization determiner compares the result with a threshold value and outputs the frequency compensation control signal based on the compared result.