Method of code generation that minimizes error propagation
First Claim
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1. A method of generating a code that minimizes error propagation, comprising the steps of:
- a) selecting an integer m, where m represents a length of unencoded bits;
b) selecting an integer n, where n represents a length of encoded bits, and where n>
m;
c) selecting a range of fractions od, where od represents a range of density values of one bits;
d) selecting in a transmission system an integer mrl, where mrl represents a maximum run length of bits;
e) generating an encoding map M, where each representation of 2^m bits is mapped to a unique representation in 2^n, and wherein the unique representations in 2^n to which the representations in 2^m are mapped satisfy od and mrl;
f) generating a decoding map N, where each representation of 2^n bits is mapped to a representation in 2^m as follows;
a. mapping each representation of 2^n bits that appears in the encoding map M to the representation of 2^m bits to which it is mapped in the encoding map M; and
b. mapping each representation of 2^n bits that does not appear in the encoding map according to the following steps;
i. determining the minimum hamming distance between the representation of 2^n bits and the representations of 2^n bits that appear in the encoding map M;
ii. determining the representations of 2^n bits that appear in the encoding map M that are within the Hamming distance determined in step (i) to the representation of 2^n bits that does not appear in the encoding map M;
iii. determining the representations in 2^m bits that correspond to the representation in 2^n bits determined in step (ii);
iv. determining a bit-majority, if any, in each bit position of the representations of 2^m bits determined in step (iii);
v. if a bit-majority is not found for a bit position then setting the bit position to the bit-majority, if any, of all of the bits in the representations on 2^m bits determined in step (iii);
vi. if a bit-majority is not found then setting the bit position to zero; and
vii. mapping the representation of 2^n bits that does not appear in the encoding map M to the bit-majority bits determined in steps (iv), (v), and (vi);
g) determining an error-propagation score for encoding map M and decoding map N; and
h) returning to step (e) if a user requires an encoding map M and a decoding map N with a lower error-propagation score than the error-propagation score determined in step (g).
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Abstract
A method of generating a code that minimizes error propagation by selecting integers m, n, mrl, and a range of fractions od, where m represents the number of bits in an unencoded sequence, where n represents the number of bits in an encoded sequence, where mrl represents the maximum run length of an encoded sequence, and where od represents a range of ones densities of an encoded sequence. Next, generating an encoding map M that maps each unencoded sequence to an n-bit encoded sequence that satisfies od and mrl. Next, generating a decoding map N that maps each n-bit sequence to an m-bit sequence. Next, determining an error-propagation score for M and N. Then, returning to the step of generating M if a user requires a lower error-propagation score.
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Citations
10 Claims
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1. A method of generating a code that minimizes error propagation, comprising the steps of:
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a) selecting an integer m, where m represents a length of unencoded bits; b) selecting an integer n, where n represents a length of encoded bits, and where n>
m;c) selecting a range of fractions od, where od represents a range of density values of one bits; d) selecting in a transmission system an integer mrl, where mrl represents a maximum run length of bits; e) generating an encoding map M, where each representation of 2^m bits is mapped to a unique representation in 2^n, and wherein the unique representations in 2^n to which the representations in 2^m are mapped satisfy od and mrl; f) generating a decoding map N, where each representation of 2^n bits is mapped to a representation in 2^m as follows; a. mapping each representation of 2^n bits that appears in the encoding map M to the representation of 2^m bits to which it is mapped in the encoding map M; and b. mapping each representation of 2^n bits that does not appear in the encoding map according to the following steps; i. determining the minimum hamming distance between the representation of 2^n bits and the representations of 2^n bits that appear in the encoding map M; ii. determining the representations of 2^n bits that appear in the encoding map M that are within the Hamming distance determined in step (i) to the representation of 2^n bits that does not appear in the encoding map M; iii. determining the representations in 2^m bits that correspond to the representation in 2^n bits determined in step (ii); iv. determining a bit-majority, if any, in each bit position of the representations of 2^m bits determined in step (iii); v. if a bit-majority is not found for a bit position then setting the bit position to the bit-majority, if any, of all of the bits in the representations on 2^m bits determined in step (iii); vi. if a bit-majority is not found then setting the bit position to zero; and vii. mapping the representation of 2^n bits that does not appear in the encoding map M to the bit-majority bits determined in steps (iv), (v), and (vi); g) determining an error-propagation score for encoding map M and decoding map N; and h) returning to step (e) if a user requires an encoding map M and a decoding map N with a lower error-propagation score than the error-propagation score determined in step (g). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification
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Current AssigneeNational Security Agency
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Original AssigneeThe United States of America As Represented By The Director National Security Agency
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InventorsEvasius, Dean M., McAdoo, Leslie Newton Jr.
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Primary Examiner(s)Chaudry; M. Mujtaba K
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Assistant Examiner(s)Ahmed; Enam
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Application NumberUS11/365,953Time in Patent Office1,471 DaysField of Search714/752, 714/723, 714/777, 714/760, 714/797, 341/59US Class Current714/752CPC Class CodesH03M 7/14 Conversion to or from non-w...
