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Serial concatenated trellis coded modulation (SCTCM) includes an outer coder, an interleaver, a recursive inner coder and a mapping element. The outer coder receives data to be coded and produces outer coded data. The interleaver permutes the outer coded data to produce interleaved data. The recursi

Serial concatenated trellis coded modulation (SCTCM) includes an outer coder, an interleaver, a recursive inner coder and a mapping element. The outer coder receives data to be coded and produces outer coded data. The interleaver permutes the outer coded data to produce interleaved data. The recursive inner coder codes the interleaved data to produce inner coded data. The mapping element maps the inner coded data to a symbol. The recursive inner coder has a structure which facilitates iterative decoding of the symbols at a decoder system. The recursive inner coder and the mapping element are selected to maximize the effective free Euclidean distance of a trellis coded modulator formed from the recursive inner coder and the mapping element. The decoder system includes a demodulation unit, an inner SISO (soft-input soft-output) decoder, a deinterleaver, an outer SISO decoder, and an interleaver.

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What is claimed is: 1. A decoding apparatus configured to decode first symbols received from a channel, wherein the first symbols correspond to output symbols transmitted onto the channel by an encoder system, wherein the encoder system is configured to perform an outer encoding on source data in o

What is claimed is: 1. A decoding apparatus configured to decode first symbols received from a channel, wherein the first symbols correspond to output symbols transmitted onto the channel by an encoder system, wherein the encoder system is configured to perform an outer encoding on source data in order to generate first data, and to perform an inner trellis coded modulation (TCM) on an interleaved version of the first data to generate the output symbols, the decoding apparatus comprising: an inner soft-input soft-output (SISO) module configured to compute first feedforward information based on input information and on first feedback information, wherein the input information is derived from the first symbols received from the encoder system, wherein the inner SISO module is configured to compute the first feedforward information based on an inner trellis defined by said inner TCM of the encoder system; a fill and multiplex (FAM) unit configured to generate augmented information by interleaving zero bits with bits of a deinterleaved version of the first feedforward information; an outer SISO module configured to compute output information and second feedback information based on the augmented information, wherein the outer SISO module is configured to compute the output information and the second feedback information based on an outer trellis defined by the outer encoding of the encoding system; and a puncture and demultiplex (PAD) unit configured to puncture the second feedback information according to a puncturing pattern, in order to generate punctured feedback information, wherein the first feedback information is an interleaved version of the punctured feedback information; wherein the inner TCM of the encoder system includes an inner encoding and a mapping, wherein the inner encoding encodes the interleaved version of the first data to generate intermediate data according to a rate 1 recursive code, wherein the mapping generates the output symbols of the inner TCM from the intermediate data according to a first map, wherein the rate 1 recursive code and the first map maximize the effective free Euclidean distance of the inner TCM. 2. The decoding apparatus of claim 1, wherein the decoding apparatus is configured to generate an estimate of at least a portion of the source data from the output information. 3. The decoding apparatus of claim 1, wherein the decoding apparatus is configured to operate said inner SISO module and said outer SISO module in an iterative fashion. 4. The decoding apparatus of claim 1, wherein the output symbols are points in a quadrature amplitude modulation (QAM) constellation, wherein the number of points in said QAM constellation is equal to 22m, wherein m is an integer greater than one. 5. The decoding apparatus of claim 1, wherein the output symbols correspond to a phase-shift keying (PSK) modulation, wherein the PSK modulation has a constellation with 2m points, wherein m is larger than one. 6. The apparatus of claim 1, wherein the outer encoding is configured to maximize free Hamming distance. 7. The apparatus of claim 6, wherein the free Hamming distance of the outer encoding is odd, wherein the rate 1 recursive code and the first map are also selected to maximize Euclidean distance d(x(z), x(z′)) over pairs z, z′ given that the Hamming distance dH(z,z′) is equal to three, wherein z and z′ are possible input sequences to the rate 1 recursive code. 8. The apparatus of claim 1, wherein the inner trellis is a 4-state trellis. 9. The apparatus of claim 1, wherein the inner trellis is a 2-state trellis. 10. A decoding apparatus configured to decode first symbols received from a channel, wherein the first symbols correspond to output symbols transmitted onto the channel by an encoder system, wherein the encoder system is configured to perform an outer encoding on source data in order to generate first data, and to perform an inner trellis coded modulation (TCM) on an interleaved version of the first data to generate the output symbols, the decoding apparatus comprising: a first means for computing first feedforward information based on input information and on first feedback information, wherein the input information is derived from the first symbols received from the encoder system, wherein said computing the first feedforward information is based on an inner trellis defined by said inner TCM of the encoder system; a second means for generating augmented information by interleaving zero bits with bits of a deinterleaved version of the first feedforward information; a third means for computing output information and second feedback information based on the augmented information, wherein said computing the output information and the second feedback information is based on an outer trellis defined by the outer encoding of the encoding system; a fourth means for puncturing the second feedback information according to a puncturing pattern in order to generate punctured feedback information, wherein the first feedback information is an interleaved version of the punctured feedback information; and wherein the inner TCM of the encoder system includes an inner encoding and a mapping, wherein the inner encoding encodes the interleaved version of the first data to generate intermediate data according to a rate 1 recursive code, wherein the mapping generates the output symbols of the inner TCM from the intermediate data according to a first map, wherein the rate 1 recursive code and the first map maximize the effective free Euclidean distance of the inner TCM. 11. The decoding apparatus of claim 10, wherein the decoding apparatus is configured to generate an estimate of at least a portion of the source data from the output information. 12. The decoding apparatus of claim 10, wherein the decoding apparatus is configured to operate said first means, said second means, said third means and said fourth means in an iterative fashion. 13. The decoding apparatus of claim 10, wherein the output symbols are points in a quadrature amplitude modulation (QAM) constellation, wherein the number of points in said QAM constellation is equal to 22m, wherein m is an integer greater than one. 14. The decoding apparatus of claim 10, wherein the output symbols correspond to a phase-shift keying (PSK) modulation, wherein the PSK modulation has a constellation with 2m points, wherein m is larger than one. 15. The apparatus of claim 10, wherein the outer encoding is configured to maximize free Hamming distance. 16. The apparatus of claim 15, wherein the free Hamming distance of the outer encoding is odd, wherein the rate 1 recursive code and the first map are also selected to maximize Euclidean distance d(x(z), x(z′)) over pairs z, z′ given that the Hamming distance dH(z,z′) is equal to three, wherein z and z′ are possible input sequences to the rate 1 recursive code. 17. The apparatus of claim 10, wherein the inner trellis is a 4-state trellis. 18. The apparatus of claim 10, wherein the inner trellis is a 2-state trellis.