Parallel concatenated tail-biting convolutional code and decoder therefor

Claim 1

A method for parallel concatenated convolutional encoding, comprising the steps of: providing a block of data bits to a parallel concatenated encoder comprising a plurality of N component encoders and N-1 interleavers connected in a parallel concatenation; encoding the block of data bits in a first one of the component encoders by applying a tail-biting nonrecursive systematic convolutional code thereto and thereby generating a corresponding first component codeword comprising the data bits and parity bits; interleaving the block of data bits to provide a permuted block of data bits; encoding the resulting permuted block of data bits in a subsequent component encoder by applying a tail-biting nonrecursive systematic convolutional code thereto, and thereby generating a corresponding second component codeword comprising the data bits and parity bits; repeating the steps of interleaving and encoding the resulting permuted block of data bits through the remaining N-2 interleavers and the remaining N-2 component encoders, and thereby generating component codewords comprising the data bits and parity bits; and formatting the bits of the component codewords to provide a composite codeword.

Claim 2

A method for parallel concatenated convolutional encoding, comprising the steps of: providing a block of data bits to a parallel concatenated encoder comprising a plurality of N component encoders and N-1 interleavers connected in a parallel concatenation; encoding the block of data bits in a first one of the component encoders by applying a tail-biting nonrecursive systematic convolutional code thereto and thereby generating a corresponding first component codeword comprising the data bits and parity bits; interleaving the block of data bits to provide a permuted block of data bits; encoding the resulting permuted block of data bits in a subsequent component encoder by applying a tail-biting nonrecursive systematic convolutional code thereto, and thereby generating a corresponding second component codeword comprising the data bits and parity bits; repeating the steps of interleaving and encoding the resulting permuted block of data bits through the remaining N-2 interleavers and the remaining N-2 component encoders, and thereby generating component codewords comprising the data bits and parity bits; and formatting the bits of the component codewords to provide a composite codeword.

Claim 5

A method for decoding parallel concatenated convolutional codes, comprising the steps of: receiving from a channel a composite codeword that comprises a formatted collection of bits from a plurality (N) of component codewords that have been generated by applying tail-biting nonrecursive systematic convolutional codes to a block of data bits in a parallel concatenated encoder, forming received component codewords from the received composite codeword, each respective received component codeword being received by a corresponding one of a plurality of N component decoders of a composite decoder, each respective component decoder also receiving a set of a priori soft-decision information for vales of the data bits; decoding the received component codewords by a process of iterations through the N component decoders and N-1 interleavers to provide soft-decision outputs from the composite decoder, the N component decoders each providing soft-decision information on each data bit in the data block in the order encoded by the corresponding component encoder, the N-1 interleavers each interleaving the soft-decision information from a preceding component decoder to provide a permuted block of soft information to a subsequent component decoder, the set of a priori soft-decision information for the first of the N component decoders being calculated assuming that the data bits' values are equally likely for the first iteration and thereafter comprising a first function of the soft-decision information, which first function of the soft-decision information is fed back from the N th component decoder via a first deinterleaver comprising N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the first deinterleaver being applied in reverse order to the N-1 interleavers, the set of a priori soft-decision information provided to each other component decoder comprising the first function of the soft-decision information from the previous sequential component decoder; and deinterleaving in a second deinterleaver to provide a second function of the soft-decision output from the N th component decoder as the composite decoder's soft-decision output using N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the second deinterleaver being applied in reverse order to the N-1 interleavers.

Claim 6

A method for decoding parallel concatenated convolutional codes, comprising the steps of: receiving from a channel a composite codeword that comprises a formatted collection of bits from a plurality (N) of component codewords that have been generated by applying tail-biting nonrecursive systematic convolutional codes to a block of data bits in a parallel concatenated encoder, forming received component codewords from the received composite codeword, each respective received component codeword being received by a corresponding one of a plurality of N component decoders of a composite decoder, each respective component decoder also receiving a set of a priori soft-decision information for vales of the data bits; decoding the received component codewords by a process of iterations through the N component decoders and N-1 interleavers to provide soft-decision outputs from the composite decoder, the N component decoders each providing soft-decision information on each data bit in the data block in the order encoded by the corresponding component encoder, the N-1 interleavers each interleaving the soft-decision information from a preceding component decoder to provide a permuted block of soft information to a subsequent component decoder, the set of a priori soft-decision information for the first of the N component decoders being calculated assuming that the data bits' values are equally likely for the first iteration and thereafter comprising a first function of the soft-decision information, which first function of the soft-decision information is fed back from the N th component decoder via a first deinterleaver comprising N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the first deinterleaver being applied in reverse order to the N-1 interleavers, the set of a priori soft-decision information provided to each other component decoder comprising the first function of the soft-decision information from the previous sequential component decoder; and deinterleaving in a second deinterleaver to provide a second function of the soft-decision output from the N th component decoder as the composite decoder's soft-decision output using N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the second deinterleaver being applied in reverse order to the N-1 interleavers.

Claim 13

A method for encoding and decoding parallel concatenated convolutional codes, comprising the steps of: providing a block of data bits to a parallel concatenated encoder comprising a plurality of N component encoders and N-1 interleavers connected in a parallel concatenation; encoding the block of data bits in a first one of the component encoders by applying a tail-biting nonrecursive systematic convolutional code thereto and thereby generating a corresponding first component codeword comprising the data bits and parity bits; interleaving the block of data bits to provide a permuted block of data bits; encoding the resulting permuted block of data bits in a subsequent component encoder by applying a tail-biting nonrecursive systematic convolutional code thereto and thereby generating a corresponding second component codeword comprising the data bits and parity bits; repeating the steps of interleaving and encoding the resulting permuted block of data bits through the remaining N-2 interleavers and the remaining N-2 component encoders, and thereby generating component codewords comprising the data bits and parity bits; formatting the bits of the component codewords to provide a composite codeword; inputting the composite codeword to a channel; receiving a received composite codeword from a channel; forming received component codewords from the received composite codeword providing each respective received component codeword to a corresponding one of a plurality of N component decoders of a composite decoder, each respective component decoder also receiving a set of a priori probabilities for values of the data bits; decoding the received component codewords by a process of iterations through the N component decoders and N-1 interleavers to provide soft-decision outputs from the composite decoder, the N component decoders each providing soft-decision information on each data bit in the data block in the order encoded by the corresponding component encoder, the N-1 interleavers each interleaving the soft-decision information from a preceding component decoder to provide a permuted block of soft information to a subsequent component decoder, the set of a priori soft-decision information for the first of the N component decoders being calculated assuming that the data bits' values are equally likely for the first iteration and thereafter comprising a first function of the soft-decision information, which first function of the soft-decision information is fed back from the N th decoder via a first deinterleaver comprising N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the first deinterleaver being applied in reverse order to the N-1 interleavers, the set of a priori soft-decision information provided to each other component decoder comprising the first function of the soft-decision information from the previous sequential component decoder; and deinterleaving in a second deinterleaver to provide a second function of the soft-decision output from the N th component decoder as the composite decoder's soft-decision output using N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the second deinterleaver being applied in reverse order to the N-1 interleavers.

Claim 14

A method for encoding and decoding parallel concatenated convolutional codes, comprising the steps of: providing a block of data bits to a parallel concatenated encoder comprising a plurality of N component encoders and N-1 interleavers connected in a parallel concatenation; encoding the block of data bits in a first one of the component encoders by applying a tail-biting nonrecursive systematic convolutional code thereto and thereby generating a corresponding first component codeword comprising the data bits and parity bits; interleaving the block of data bits to provide a permuted block of data bits; encoding the resulting permuted block of data bits in a subsequent component encoder by applying a tail-biting nonrecursive systematic convolutional code thereto and thereby generating a corresponding second component codeword comprising the data bits and parity bits; repeating the steps of interleaving and encoding the resulting permuted block of data bits through the remaining N-2 interleavers and the remaining N-2 component encoders, and thereby generating component codewords comprising the data bits and parity bits; formatting the bits of the component codewords to provide a composite codeword; inputting the composite codeword to a channel; receiving a received composite codeword from a channel; forming received component codewords from the received composite codeword providing each respective received component codeword to a corresponding one of a plurality of N component decoders of a composite decoder, each respective component decoder also receiving a set of a priori probabilities for values of the data bits; decoding the received component codewords by a process of iterations through the N component decoders and N-1 interleavers to provide soft-decision outputs from the composite decoder, the N component decoders each providing soft-decision information on each data bit in the data block in the order encoded by the corresponding component encoder, the N-1 interleavers each interleaving the soft-decision information from a preceding component decoder to provide a permuted block of soft information to a subsequent component decoder, the set of a priori soft-decision information for the first of the N component decoders being calculated assuming that the data bits' values are equally likely for the first iteration and thereafter comprising a first function of the soft-decision information, which first function of the soft-decision information is fed back from the N th decoder via a first deinterleaver comprising N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the first deinterleaver being applied in reverse order to the N-1 interleavers, the set of a priori soft-decision information provided to each other component decoder comprising the first function of the soft-decision information from the previous sequential component decoder; and deinterleaving in a second deinterleaver to provide a second function of the soft-decision output from the N th component decoder as the composite decoder's soft-decision output using N-1 deinterleavers corresponding to the N-1 interleavers, the N-1 deinterleavers of the second deinterleaver being applied in reverse order to the N-1 interleavers.