Method and apparatus for error control coding in communication systems using an outer interleaver

A turbo encoder system for encoding a digital signal including a codeword having a plurality of symbols, comprising:

• a Reed-Solomon encoder, for receiving and encoding the codeword;
• a Forney interleaver, for receiving from the Reed Solomon encoder, the encoded codeword, and for interleaving the symbols in the codeword according to a predetermined interleaver index;
• and
• a turbo encoder for receiving the interleaved encoded codeword from the Forney interleaver, the turbo encoder having at least one modified dithered relatively prime interleaver for interleaving the codeword, at least two RSC encoders for encoding the codeword and the interleaved codeword, respectively, and a puncturer for puncturing the codeword, the encoded codeword, and the interleaved and encoded codeword to provide a turbo codeword.

A turbo coding method, comprising the steps of:

• encoding a plurality of codewords according to a Reed-Solomon (RS) outer code;
• interleaving the plurality of RS encoded codewords using a Forney interleaver;
• providing each of the plurality of interleaved codewords to a first RSC encoder for encoding using a systematic recursive convolutional constituent (RSCC) code to provide first purity bits;
• providing each of the plurality of interleaved codewords to an interleaver coupled to a second RSC encoder for interleaving each codeword and for encoding each doubly interleaved codeword using a RSCC code to provide second parity bits;
• puncturing the first and second parity bits in accordance with a pattern of a desired code rate;
• and
• mapping the punctured parity bits to provide signal sets in accordance with the desired code rate.