Apparatus for generating codes in communication system
A QCTC (Quasi-Complementary Turbo Code) generating apparatus having a turbo encoder for generating an information symbol sequence and a plurality of parity symbol sequences by encoding the information symbol sequence; a channel interleaver for individually interleaving the symbol sequences, generating new parity symbol sequences by multiplexing the symbols of parity symbol sequences with the same priority levels, and serially concatenating the information symbol sequence and the new parity symbol sequences; and a QCTC generator for generating a sub-code with a given code rate by recursively selecting a predetermined number of symbols from the concatenated symbol sequence at a given starting position.
1. A QCTC (Quasi-Complementary Turbo Code) generating apparatus comprising:
a turbo encoder having a plurality of constituent encoders, for receiving information bits, generating a plurality of parity symbol sequences according to a given code rate by encoding the information bits, and outputting an information symbol sequence and the plurality of parity symbol sequences, each of the constituent encoders for generating at least one parity symbol sequence, the at least one parity symbol sequence from one constituent encoder corresponding to the at least one parity symbol sequence from another constituent encoder;
a channel interleaver for individually interleaving the information symbol sequence and the parity symbol sequences, alternately arranging the interleaved symbols of the corresponding parity symbol sequences, and serially concatenating the interleaved information symbol sequence and the arranged interleaved parity symbol sequences; and
a QCTC generator for generating a sub-code of a QCTC by repeating the serially concatenated symbol sequence and selecting a predetermined number of symbols from the repeated symbol sequence according to code rate and selection information.
2. The QCTC generating apparatus of claim 1 , wherein the channel interleaver comprises:
a plurality of interleavers for individually interleaving the information symbol sequence and the plurality of parity symbol sequences;
a multiplexer for generating a new parity symbol sequence by multiplexing the interleaved symbols of the corresponding parity symbol sequences; and
a symbol concatenator for serially concatenating the interleaved information symbol sequence and the new parity symbol sequence.
3. The QCTC generating apparatus of claim 1 , wherein the QCTC generator comprises:
a symbol repeater for repeating the serially concatenated symbol sequence; and
a symbol selector for generating the sub-code by selecting a predetermined number of symbols from the repeated symbol sequence at a given starting position according to a given code rate.
4. The QCTC generating apparatus of claim 3 , wherein the given starting position is the position of a symbol following the last symbol selected for the previous transmission.
5. The QCTC generating apparatus of claim 1 , wherein the QCTC generator comprises:
a circular buffer memory for storing the serially concatenated symbol sequence; and
a symbol selector for generating the sub-code by selecting a predetermined number of symbols from the serially concatenated symbol sequence at a given starting position according to a given code rate.
6. The QCTC generating apparatus of claim 5 , wherein the given starting position is the position of a symbol following the last symbol selected for the previous transmission.
7. The QCTC generating apparatus of claim 1 , wherein the QCTC generator generates the sub-code by selecting a predetermined number of symbols from the repeated symbol sequence according to a given code rate, starting with a symbol following the last symbol selected for the previous transmission.
8. The QCTC generating apparatus of claim 1 , wherein the channel interleaver individually interleaves the information symbol sequence and the plurality of parity symbol sequences by PBRO (Partial Bit Reversal Order) interleaving.
9. A QCTC (Quasi-Complementary Turbo Code) generating apparatus comprising:
a turbo encoder for receiving information bits, generating a plurality of parity symbol sequences by encoding the information bits, and outputting an information symbol sequence and the plurality of parity symbol sequences;
a channel interleaver for individually interleaving the information symbol sequence and the parity symbol sequences, generating new parity symbol sequences by multiplexing the interleaved symbols of parity symbol sequences, and serially concatenating the information symbol sequence and the new parity symbol sequences; and
a QCTC generator for generating a sub-code of a QCTC with a given code rate by selecting a predetermined number of symbols from the serially concatenated symbol sequence at a given starting position according to the code rate.
10. The QCTC generating apparatus of claim 9 , wherein the turbo encoder comprises a plurality of constituent encoders, each constituent encoder generating at least one parity symbol sequence, and at least one interleaver, wherein a primary parity symbol sequence from each constituent encoder has a higher priority level.
11. The QCTC generating apparatus of claim 9 , wherein the given starting position is the position of a symbol following the last symbol selected for the previous transmission.