A bit interleaving method involves applying a bit permutation process to a QC LDPC codeword made up of N cyclic blocks each including Q bits, and dividing the codeword, after the bit permutation process, into a plurality of constellation words each imade up of M bits, the codeword being divided into N/M sections, each constellation word being associated with one of the N/M sections, and the bit permutation process being performed such that each of the constellation words includes one bit from each of M different cyclic blocks associated with a given section.

A transmitter is provided. The transmitter includes: a Low Density Parity Check (LDPC) encoder configured to encode input bits to generate parity bits; a parity permutator configured to group-wise interleave a plurality of bit groups including the parity bits; and a puncturer configured to select some of the parity bits in the group-wise interleaved bit groups and puncture the selected parity bits, wherein the parity permutator group-wise interleaves the bit groups such that some of the bit groups at predetermined positions in the bit groups before the group-wise interleaving are positioned serially after the group-wise interleaving and a remainder of the bit groups before the group-wise interleaving are positioned without an order after the group-wise interleaving so that the puncturer selects parity bits included in the some of the bit groups sequentially and selects parity bits included in the remainder of the bit groups without an order.

A method and an apparatus for transmitting broadcast signals thereof are disclosed. The apparatus for transmitting broadcast signals comprises an encoder for encoding service data, a mapper for mapping the encoded service data into a plurality of OFDM (Orthogonal Frequency Division Multiplex) symbols to build at least one signal frame, a frequency interleaver for frequency interleaving data in the at least one signal frame by using a different interleaving-seed which is used for every OFDM symbol pair comprised of two sequential OFDM symbols, a modulator for modulating the frequency interleaved data by an OFDM scheme and a transmitter for transmitting the broadcast signals having the modulated data, wherein the different interleaving-seed is generated based on a cyclic shifting value and wherein an interleaving seed is variable based on an FFT size of the modulating.

A transmitting apparatus and a receiving apparatus are provided. The transmitting apparatus includes: an encoder configured to generate a low density parity check (LDPC) codeword by LDPC encoding based on a parity check matrix; an interleaver configured to interleave the LDPC codeword; and a modulator configured to map the interleaved LDPC codeword onto a modulation symbol, wherein the modulator is further configured to map a bit included in a predetermined bit group from among a plurality of bit groups constituting the LDPC codeword onto a predetermined bit of the modulation symbol.

A coding method for data communication is provided, and may be applied to a plurality of scenarios such as a metro network, a backbone network, and a data center interconnection. The method includes: forming a first codeword, where the first codeword includes n image bits and n to-be-transmitted bits, the n image bits are selected from to-be-transmitted bits in m source codewords, the source codeword is a codeword formed before the first codeword, both n and m are positive integers, and n>m; and sending the n to-be-transmitted bits in the first codeword. The bit in the first codeword is protected by a plurality of codewords generated at different moments, and a coding gain effect is better. In addition, the bit in the codeword is protected by different quantities of codewords.

A signal receiving method include: demodulating a signal received from a transmitting apparatus to generate values based on 1024-quadrature amplitude modulation (QAM); splitting the values into a plurality of groups; deinterleaving the plurality of groups based on a preset interleaving order; and decoding values of the deinterleaved plurality of groups based on a low density parity check (LDPC) code, a code rate of the LDPC code being 6/15 and a code length of the LDPC code being 64800, wherein the plurality of groups are deinterleaved based on a predetermined equation.

A transmission device, a transmission method, a reception device, and a reception method for securing good communication quality in data transmission using an LDPC code. The LDPC coding is performed using a parity check matrix with the code length N of 17280 bits and the coding rate r of 13/16 or 14/16. The LDPC code includes information bits and parity bits, and the parity check matrix includes an information matrix portion corresponding to the information bits and a parity matrix portion corresponding to the parity bits. The information matrix portion is represented by a parity check matrix initial value table, and the parity check matrix initial value table is a table representing positions of elements of 1 of the information matrix for every 360 columns.

A convolutional interleaver included in a time interleaver, which performs convolutional interleaving includes: a first switch that switches a connection destination of an input of the convolutional interleaver to one end of one of a plurality of branches; a FIFO memories provided in some of the plurality of branches except one branch, wherein a number of FIFO memories is different among the plurality of branches; and a second switch that switches a connection destination of an output of the convolutional interleaver to another end of one of the plurality of branches. The first and second switches switch the connection destination when the plurality of cells as many as the codewords per frame have passed, by switching a corresponding branch of the connection destination sequentially and repeatedly among the plurality of branches.

A bit interleaver, a bit-interleaved coded modulation (BICM) device and a bit interleaving method are disclosed herein. The bit interleaver includes a first memory, a processor, and a second memory. The first memory stores a low-density parity check (LDPC) codeword having a length of 64800 and a code rate of 4/15. The processor generates an interleaved codeword by interleaving the LDPC codeword on a bit group basis. The size of the bit group corresponds to a parallel factor of the LDPC codeword. The second memory provides the interleaved codeword to a modulator for 1024-symbol mapping.

A key-based interleaver for enhancement the security of wireless communication includes a physical layer communication channel key to provide security even when the software encryption key is compromised. A method of creating a secure communication link using a physical layer interleaving system includes implementing a key policy implementation that utilizes temporal dependency and interleaving bits using a flexible inter and intra-block data interleaver.