Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals
A method and an apparatus for transmitting broadcast signals thereof are disclosed. The apparatus for transmitting broadcast signals comprises an encoder for encoding DP (Data Pipe) data corresponding to each of a plurality of DPs, wherein the each of a plurality of DPs carries at least one service component, a mapper for mapping the encoded DP data onto constellations, a time interleaver for time interleaving the mapped DP data at DP level by skipping cells having zero values of the DP data, a frame builder for building at least one signal frame including the time interleaved DP data, a modulator for modulating data in the built at least one signal frame by an OFDM (Orthogonal Frequency Division Multiplex) scheme and a transmitter for transmitting the broadcast signals having the modulated data.
1. A method for transmitting broadcast signals, the method comprising:
encoding Data Pipe (DP) data corresponding to each of a plurality of DPs;
bit interleaving the encoded DP data;
mapping the bit interleaved DP data onto constellations;
time interleaving the mapped DP data at DP level by skipping a part of cells which are included in a time interleaving block when a number of columns of the time interleaving block is smaller than a number of columns of a time interleaving memory;
building at least one signal frame including the time interleaved DP data;
modulating data in the built at least one signal frame by an Orthogonal Frequency Division Multiplex (OFDM) scheme; and
transmitting the broadcast signals having the modulated data,
wherein the time interleaving further includes:
performing a column-wise writing operation by writing forward error correction (FEC) blocks of the mapped DP data into a first column to a last column of a time interleaving memory; and
performing a diagonal-wise reading operation by diagonal-wise reading out cells of the written FEC blocks from a first row to a last row of the time interleaving memory,
wherein the diagonal-wise reading operation includes:
calculating positions for the cells in the time interleaving block,
wherein a position of each cell is represented as:
N r c k +r k
wherein Nr is a row size of the time interleaving memory, ck is a column index of the each cell, and rk is a row index of the each cell.
2. The method of claim 1 , wherein the
column index is generated based on a twisting parameter.
3. The method of claim 1 , wherein the
time interleaving block includes at least one virtual FEC block, and
wherein the skipping a part of cells is performed based on the position for cells and a number of cells included in the at least one virtual FEC block.
4. The method of claim 1 , wherein the diagonal-wise reading operation further includes:
skipping the cells during the diagonal-wise reading operation based on the calculated positions of the cells.
5. An apparatus for transmitting broadcast signals, the apparatus comprising:
an encoder to encode Data Pipe (DP) data corresponding to each of a plurality of DPs;
a bit interleaver to bit interleave the encoded DP data;
a mapper to map the bit interleaved DP data onto constellations;
a time interleaver to time interleave the mapped DP data at DP level by skipping a part of cells which are included in a time interleaving block when a number of columns of the time interleaving block is smaller than a number of columns of a time interleaving memory;
a frame builder to build at least one signal frame including the time interleaved DP data;
a modulator to modulate data in the built at least one signal frame by an Orthogonal Frequency Division Multiplex (OFDM) scheme; and
a transmitter to transmit the broadcast signals having the modulated data,
wherein the time interleaver further performs a column-wise writing operation by writing forward error correction (FEC) blocks of the mapped DP data into a first column to a last column of a time interleaving memory and performs a diagonal-wise reading operation by diagonal-wise reading out cells of the written FEC blocks from a first row to a last row of the time interleaving memory,
wherein the diagonal-wise reading operation includes:
calculating positions for the cells in the time interleaving block, wherein a position of each cell is represented as:
N r c k +r k ,
wherein Nr is a row size of the time interleaving memory, ck is a column index of the each cell, and rk is a row index of the each cell.
6. The apparatus of claim 5 , wherein the column index is generated based on a twisting parameter.
7. The apparatus of claim 5 , wherein the
time interleaving block includes at least one virtual FEC block,
wherein the skipping a part of cells is performed based on the position for cells and a number of cells included in the at least one virtual FEC block.
8. The apparatus of claim 5 , wherein the diagonal-wise reading operation further includes:
skipping the cells during the diagonal-wise reading operation based on the calculated positions of the cells.