Method for protecting important data bits using less important data bits
First Claim
1. An apparatus for coding information bits for transmission, comprising:
- a separator for sorting the information bits into a first group of information bits and a second group of information bits;
a first convolutional encoder for coding the first group of information bits to produce a third group of coded information bits;
a second convolution encoder for coding the second group of information bits to produce a fourth group of coded information bits, wherein a ratio of the third group of information bits to the first group of information bits is greater than a ratio of the fourth group of information bits to the second group of information bits;
scrambling circuitry for scrambling the fourth group of coded information bits in dependence on the first group of information bits to produce a fifth group of scrambled, coded information bits; and
a transmitter for transmitting each of the fifth group of scrambled, coded information bits and each of the third group of coded information bits in a predetermined transmission sequence.
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Accused Products
Abstract
A method and apparatus for protecting a first group of data bits using a second group of data bits within digital data transmissions is disclosed. First and second groups of data bits are encoded for transmission in a communication network. The second group of encoded data bits are scrambled using a scrambling mask generated from the first group of data bits. The first group of encoded data bits and the second group of encoded and scrambled data bits are then interleaved and transmitted to a receiver. The first group of data bits are decoded and used to regenerate the scrambling mask to descramble the second group of encoded and scrambled data bits. The second group of data bits may then be decoded. The results of the decoding of the second group of data bits are used to determine whether or not the first group of data bits were properly decoded.
118 Citations
32 Claims
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1. An apparatus for coding information bits for transmission, comprising:
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a separator for sorting the information bits into a first group of information bits and a second group of information bits; a first convolutional encoder for coding the first group of information bits to produce a third group of coded information bits; a second convolution encoder for coding the second group of information bits to produce a fourth group of coded information bits, wherein a ratio of the third group of information bits to the first group of information bits is greater than a ratio of the fourth group of information bits to the second group of information bits; scrambling circuitry for scrambling the fourth group of coded information bits in dependence on the first group of information bits to produce a fifth group of scrambled, coded information bits; and a transmitter for transmitting each of the fifth group of scrambled, coded information bits and each of the third group of coded information bits in a predetermined transmission sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for receiving a signal and decoding therefrom coded and scrambled information bits to produce a first and a second group of information bits, comprising:
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a first processor for hypothesizing in dependence on a metric value a plurality of first sequences of bits containing the first group of information bits to determine a first sequence of bits with a cumulative metric indicative of a highest likelihood; a first re-encoder for re-encoding the hypothesized plurality of first sequences of bits to produce first expected signal samples corresponding to the first group of information bits; a first metric accumulator for comparing the first expected signal samples with a corresponding received signal samples and for accumulating a cumulative metric associated with the first expected signal samples based on the comparison; unscrambling circuitry for unscrambling the received signal samples corresponding to a second group of information bits based on the determined first group of information bits of highest likelihood; a second processor for successively hypothesizing a second bit sequence containing the second group of information bits dependant on a plurality of stored metric values to determine the second bit sequence having a second cumulative metric indicative of a highest likelihood; a second re-encoder for re-encoding the hypothesized second bit sequence to produce a sequence of second expected signal samples corresponding to a second group of information bits; a second metric accumulator for comparing unscrambled received signal to the sequence of second expected signal samples and for accumulating a plurality of second cumulative metrics based on the comparisons; and error indicating circuitry for processing the first cumulative metric indicating highest likelihood with the second cumulative metric indicating highest likelihood to produce an error indicator signal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. An apparatus for receiving a signal and decoding therefrom coded and scrambled information bits to produce a first group of decoded information bits corrected for transmission errors plus an indicator signal warning of the likelihood of uncorrected errors and a second group of information bits corrected for some transmission errors, comprising:
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a first processor for successively hypothesizing first sequences of bits containing said first group of information bits in dependence on metric values to determine a first sequence of bits having a first cumulative metric indicative of highest likelihood; a first re-encoder for re-encoding said hypothesized first sequences of bits to produce sequences of first expected signal samples corresponding to said first group of information bits; a first metric accumulator for comparing said first expected signal samples with corresponding received signal samples and accumulating said cumulative metrics based on similarity or difference; a second processor for successively hypothesizing second sequences containing said second group of information bits in dependence on metric values to determine a second sequence of bits having a second cumulative metric indicative of highest likelihood; a second re-encoder for re-encoding said hypothesized second sequence of bits to produce a sequence of second expected signal samples corresponding to said second group of information bits; scrambling circuitry for scrambling said second expected signal samples corresponding to said second group of information bits using said determined first sequence of information bits of highest likelihood; a second metric accumulator for comparing said received signal samples with said scrambled expected signal samples and accumulating said second cumulative metrics based on similarity or difference; and error indicator circuitry for processing said first cumulative metric indicative of highest likelihood with said second cumulative metric indicative of highest likelihood to produce said indicator signal.
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30. A method for encoding information bits comprising the steps of:
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sorting information bits into a first group of bits and a second group of bits; selecting a first number of adjacent bits within the first group of bits and the second group of bits including only bits of the first group; calculating a first number of coded bits from the first number of adjacent bits; selecting a second number of adjacent bits from the first group of bits and the second group of bits including only bits of the second group; calculating a second number of coded bits from the second number of adjacent bits; and scrambling said second number of coded bits in dependence on the first number of coded bits to produce a third group of coded bits. - View Dependent Claims (31)
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32. A method for decoding a coded information signal containing a first set of coded symbols corresponding to a first set of information symbols and a second set of scrambled and coded symbols corresponding to a second set of information symbols, comprising the steps of:
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processing a first portion of the coded information signal containing the first set of coded symbols to generate a number of hypotheses for the first set of information symbols and an associated likelihood metric; processing a second portion of the coded information signal containing the second set of scrambled and coded symbols using the number of hypotheses for the first set of information symbols to unscramble and decode the scrambled and coded symbols and to compute an updated likelihood metric; and selecting one of the number of hypotheses with a highest likelihood metric and extracting the first and second sets of information symbols therefrom as desired decoded symbols when the one of the hypotheses has been extended to include all of the first and second set of information symbols.
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Specification