Method and apparatus for generating super-orthogonal convolutional codes and the decoding thereof
First Claim
1. An apparatus for convolutional encoding of information bits comprising:
- data converter means for receiving a serial input of information bits and for providing, for each received input information bit, a corresponding parallel output of a group of K most recently received ones of said received information bits, a most recently received information bit through a least recently received information bit respectively identified as first through Kth information bits; and
orthogonal sequence generator means for receiving each group of K information bits, for performing a logical "exclusive-or" operation on said first and Kth information bits of each received group of K information bits, for generating for each each received group of K information bits a plurality of predetermined sequences of K-2 binary count bits, for performing a logical "and" operation on each one of a second through a K-1 information bit of each received group of K information bits with respect to a corresponding binary count bit in each sequence of binary count bits, for performing a parity check on a result of each set of logical "and" operations and a result of said logical "exclusive-or" operation, and for providing a resultant output sequence of 2K-2 symbols.
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Abstract
An encoder and decoder for generating and decoding convolutional codes of enhanced orthogonality. In an exemplary embodiment the encoder includes a K bit length shift register for receiving an input serial stream of information bits and providing for each input bit a K bit parallel output to an orthogonal code sequence generator where one of 2K-1 symbol sequences is generated with each symbol sequence of a K-2 symbol length. The encoded symbol stream is decoded using an orthogonal function generator driven by a K-2 binary counter to generate all possible symbol sequences for comparison with each received symbol sequence. The output of the comparison is Viterbi decoded to provide the original stream of information bits. Corresponding methods of encoding the information bits and decoding of the symbol sequences are included.
121 Citations
20 Claims
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1. An apparatus for convolutional encoding of information bits comprising:
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data converter means for receiving a serial input of information bits and for providing, for each received input information bit, a corresponding parallel output of a group of K most recently received ones of said received information bits, a most recently received information bit through a least recently received information bit respectively identified as first through Kth information bits; and orthogonal sequence generator means for receiving each group of K information bits, for performing a logical "exclusive-or" operation on said first and Kth information bits of each received group of K information bits, for generating for each each received group of K information bits a plurality of predetermined sequences of K-2 binary count bits, for performing a logical "and" operation on each one of a second through a K-1 information bit of each received group of K information bits with respect to a corresponding binary count bit in each sequence of binary count bits, for performing a parity check on a result of each set of logical "and" operations and a result of said logical "exclusive-or" operation, and for providing a resultant output sequence of 2K-2 symbols. - View Dependent Claims (2, 3, 4)
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5. A method for convolutional encoding information bits comprising the steps of:
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converting a serial input of information bits into a corresponding parallel output of the K most recently received information bits of said serial input of information bits wherein a most recently received information bit through a least recently received information bit are respectively identified as first through Kth information bits; performing a logical "exclusive-or" operation on said first and Kth information bits; generating, for each input of an information bit of said serial input of information bits, a plurality of predetermined sequences of K-2 binary count bits wherein each bit position in each sequence of K-2 binary count bits corresponds to a second through K-1 information bits; performing a logical "and" operation on each respective one of said second through K-1 information bits with respect to each corresponding binary count bit in each sequence of binary count bits; performing a parity check on a result of each logical "and" operations and a result of said logical "exclusive-or" operation; and providing an output sequence of 2K-2 symbols. - View Dependent Claims (6)
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7. A data encoder comprising:
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a register having an input for receiving an input sequence of data bits, and having a first through a K output at which is provided a respective one of the last K received bits of said input sequence of data bits; an input EXCLUSIVE OR gate having a pair of inputs respectively coupled to said first and K outputs of said register, and an output; an orthogonal function sequence generator having K-2 inputs each coupled to a respective one of a second through a K-1 output of said register, and having an output; and an output EXCLUSIVE OR gate having a pair of inputs respectively coupled to said first EXCLUSIVE OR gate output and said generator output, and an output. - View Dependent Claims (8, 9, 10)
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11. A decoder for decoding orthogonal convolutional coded data comprising:
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orthogonal function generator means for generating and providing an output of a plurality of predetermined orthogonal function sequences; combining means for, receiving and combining an input of encoded symbol data with said plurality of orthogonal function sequences, and providing a corresponding output; accumulator means for, receiving and accumulating said combining means output, and providing a corresponding output; and Viterbi decoder means for receiving said accumulator means output as branch metric data and computing from said branch metric data corresponding bit data. - View Dependent Claims (12, 13, 14)
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15. A decoder comprising:
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a first memory having an input for receiving an input of encoded symbol data and an output; a multiplier having a pair of inputs and an output, one input of said multiplier coupled to said first memory output; a K-2 bit binary counter having a counter clock input and an output; an orthogonal function sequence generator having a generator clock input, a data input and an output, said generator data input coupled to said counter output and said generator output coupled to another input of said multiplier; an accumulator having an input coupled to said multiplier output, and an output; a second memory having an input coupled to said accumulator output, and an output; and a Viterbi decoder having an input coupled to said second memory output, and and output at which bit data is provided. - View Dependent Claims (16, 17)
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18. A method for decoding orthogonal convolutional coded data comprising:
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receiving an input of orthogonal convolutional encoded symbol data; generating a plurality of predetermined orthogonal function sequences; combining said received input of symbol data with said plurality of orthogonal function sequences so a to provide a corresponding combined data; accumulating said combined data so as to provide a corresponding accumulated data; providing said accumulated data as branch metric data to a Viterbi decoder; computing from said branch metric data within said Viterbi decoder corresponding bit data; and providing an output of said bit data from said Viterbi decoder. - View Dependent Claims (19, 20)
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Specification