Abstract: An apparatus is capable of distributing power over a number of subcarriers in an OFDM system. The transmission power control method for an Orthogonal Frequency Division Multiplexing (OFDM) communication system according to the present invention includes measuring, at a receiver, channel coefficients of subcarriers, classifying the subcarriers into a predetermined number of groups according to sizes of channel coefficients, generating group indices, and transmitting the group indices of the subcarriers to a transmitter. A transmitter is capable of receiving the group indices of the subcarriers, determining per-group transmission powers, allocating the per-group transmission powers to the corresponding groups, distributing the per-group transmission power over subcarriers in the same level within respective groups, and transmitting signals over the subcarriers with the distributed power level.

Abstract: A Digital Video Broadcasting-Cable (DVB-C) system and a processing method for reserved tones are provided. A transmitter determines a position of broadcast data and a position of reserved tones in a frame and sends a broadcast signal into which the broadcast data and the reserved tones are inserted. A receiver determines the position of reserved tones in a received broadcast signal and extracts broadcast data from the broadcast signal in consideration of the determined position of the reserved tones. The system and method may compensate for the peak power of broadcast data to be transmitted through a multi-channel bundle, by inserting reserved tones into the whole multi-channel bundle with combined channel bands. This may reduce the Peak to Average Power Ratio (PAPR) of broadcast signals in the DVB-C system and thereby improve the performance of the DVB-C system while still adopting Orthogonal Frequency Division Multiplexing (OFDM).

Abstract: An apparatus and method for transmitting/receiving an urgent packet in a digital broadcast system is provided. A packet transmission apparatus of a digital broadcast transmitter includes a buffer which buffers broadcast packets; an urgent packet generator which generates an urgent packet having an urgent packet header indicating the urgent packet when a packet containing urgent data is detected; and a frame generator which generates a frame with the broadcast packets and inserts the urgent packet into the frame, wherein the urgent packet is substituted for one of broadcast packets in the frame.

Abstract: An improved bit mapping method and apparatus for a communication system is provided. A bit mapping method of the present invention includes arranging coded bits in a codeword in an order of recovery capability; setting a shift region including a number of coded bits; rearranging the coded bits in the shift region by shifting the shift region by a number of bits equal to a number of bits that is indicated by a shift factor; and mapping the rearranged coded bits into a modulation symbol in an order of reliability from a lowest reliability bit position to a highest reliability bit position of the modulation symbol.

Abstract: An encoding method using a Low Density Parity Check (LDPC) matrix having a codeword length of N and an information word length K is provided to improve coding efficiency, and includes generating a first parity bit vector (p1) using the low density parity check matrix, generating a second parity bit vector (p2), performing L-parallel iterative accumulation encoding on the first parity bit vector, and generating a codeword vector c=(s,p1,p2) including an information word vector and the first and second parity bit vectors. The communication method and apparatus herein provides an efficient encoding algorithm using the trade-off relationship between a circuit implementation and operation and delay complexities.

Abstract: A method and apparatus for transmitting and receiving a preamble having sequence information for an OFDM system is provided. The preamble transmission method includes generating a preamble block including at least one frame having a header with a known sequence and a code block containing control information and transmitting the preamble block mapped to Orthogonal Frequency Division Multiplexing (OFDM) cells by repeating in frequency axis direction.

Abstract: An encoding/decoding apparatus and method using a low-density parity-check code (LDPC code) is disclosed. Basic column group information, serving as a set of information regarding positions of rows with weight 1, is extracted from a reference column in each column group of a predetermined parity-check matrix. Column group information transforms the positions of rows with weight 1 into positions whose lengths are within a required parity length. A parity-check matrix is generated according to the generated column group information. Data is encoded or decoded based on the generated parity-check matrix.

Abstract: A method and apparatus for reducing a Peak to Average Power Ratio (PAPR) in a digital broadcasting system are provided. Reserved tones are determined, and the determined reserved tones are used to transmit a signal having an impulse characteristic in locations of sub-carriers that do not collide with a pilot signal of a preamble in a frame. The signal having the impulse characteristic is transmitted through the reserved tones in a symbol interval for which the preamble is transmitted.

Abstract: A method and apparatus for transmitting control information in a wireless communication system using a Low Density Parity Check (LDPC) code is provided. The number of LDPC blocks, through which L1 post-signaling information is to be transmitted, is determined according to the total number of bits of the L1 post-signaling information. The number of input information bits of each LDPC block is calculated when the determined number of LDPC blocks is plural. The number of puncturing bits among parity bits of each LDPC block is determined considering a modulation order. A frame including one or multiple LDPC blocks generated through the preceding steps is transmitted.

Abstract: An apparatus and a method for channel encoding/decoding in a communication system are provided. The apparatus and the method generate LDPC-encoded blocks with various lengths from an LDPC code with fixed length in a communication system using a Low-Density Parity-Check (LDPC) code. The apparatus and the method perform shortening using a predetermined number of shortened bits and perform LDPC encoding. The apparatus and the method apply predetermined rules according to the predetermined number of shortened bits and determine the number of bits to be punctured, and perform puncturing based on the determined number of punctured bits.

Abstract: A method is provided for transmitting in-band signaling information in a wireless broadcasting system that transmits broadcast service data through a plurality of data Physical Layer Pipes (PLPs) constituting a frame. Non-PLP signaling information is included in a data PLP for a particular broadcast service and the data PLP is transmitted through a current frame, when no data PLP for the particular broadcast service is transmitted in at least one frame to be transmitted within a maximum schedulable period NMAX from a time the current frame is transmitted. The non-PLP signaling information indicates that no data PLP for the particular broadcast service is transmitted within the maximum schedulable period.

Abstract: A method and apparatus for transmitting/receiving control information in a wireless communication system are provided, in which physical layer signaling information to be transmitted in a frame is determined, a coded block is generated from signaling information having a fixed number of bits included in the physical layer signaling information, and a frame including the coded block is transmitted. The signaling information having the fixed number of bits includes information required for receiving other signaling information having a variable number of bits.

Abstract: Apparatus and method for transmitting and receiving a frame including control information in a broadcasting system. A frame for a broadcast service is generated using an in-band signaling scheme, and includes location information of control information in a next frame and indication information indicating a change/no-change in the control information in the next frame. The new frame structure minimizes power consumption of a receiver supporting the broadcast service.

Abstract: An apparatus and method for generating a parity-check matrix of a Low-Density Parity-Check (LDPC) code are provided. Parameters for designing the LDPC code are determined, and a first parity-check matrix of a quasi-cyclic LDPC code is formed according to the determined parameters. A second parity-check matrix is created through the elimination of a predetermined portion of a parity part in the first parity-check matrix, and a third parity-check matrix is created by rearranging the second parity-check matrix.

Abstract: An apparatus and method for encoding a channel in a communication system using a Low-Density Parity-Check (LDPC) code. The method includes determining a number of parity bits to be subjected to puncturing; dividing the parity bits at predetermined intervals, and determining a number of puncturing bits, which are subjected to puncturing within the predetermined intervals; determining positions of puncturing parity bits corresponding to the determined number of puncturing bits; and repeatedly performing puncturing on the puncturing parity bits corresponding to the determined positions at the predetermined intervals. The predetermined intervals are determined by dividing a length of parity bits by a length of one column group in a parity-check matrix.

Abstract: An apparatus and method for configuring a broadcast service data in a digital broadcasting communication system are provided. The method includes mapping a first zone, corresponding to broadcast service data of a first type, and a second zone, corresponding to broadcast service data of a second type, in a frame individually. Preferably, the broadcast service data included in the first zone and the second zone is sliced into sub-slices according to a different number of service slicings for each zone.

Abstract: An apparatus and method for transmitting a preamble in a Digital Video Broadcasting (DVB) system are provided. The apparatus includes a first processor for generating a Modulation Signaling Sequence (MSS) using a plurality of received sequences, and for outputting a modulated sequence by differentially modulating the MSS. The apparatus also includes a scrambler for scrambling the modulated sequence by multiplying the modulated sequence by a scrambling sequence. A second processor receives the scrambled sequence through each allocated subcarrier, converts the received sequence into a time-domain signal, and generates and transmits the preamble.

Abstract: A method for encoding a channel in a communication system using a Low-Density Parity-Check (LDPC) code. The method includes generating a plurality of column groups by grouping (categorizing) columns corresponding to an information word in a parity-check matrix of the LDPC code, and ordering the column groups; determining a range of an information word desired to be obtained by performing shortening; based on the determined range of the information word, performing column group-by-column group shortening on the column groups in order according to a predetermined shortening pattern; and LDPC encoding the shortened information word.

Abstract: Disclosed is a method and apparatus for transmitting/receiving control information in a system in which one or more Radio Frequencies (RFs) are used to carry multiple services through a frame constituted by time resources or time-frequency resources. Control information regarding frame configuration information is not transmitted over a separate control channel but over a data channel through which to transmit primary service traffic among all service traffic, and each non-primary service traffic other than the primary service traffic includes control information for a primary service. Thus, even when a receiver changes the current service to a target service, control information necessary to detect the location of the target service in a frame and demodulate the target service can be acquired, and thus a service change can be made without reading a separate control channel.

Abstract: A method is provided for transmitting control information by a Base Station (BS) in a Time Division Duplexing (TDD)-based Orthogonal Frequency Division Multiple Access (OFDMA) system. The method includes determining a TDD ratio value; when a value obtained by dividing a number of consecutive Forward-Link (FL) time slots of a predetermined time interval by a number of consecutive Reverse-Link (RL) time slots is not a positive integer, grouping Mobile Stations (MSs) into multiple groups and generating group index information; and transmitting, to the MSs, control information including the TDD ratio value and the group index information.