Analysis of error floor of LDPC codes under LP decoding over the BSC

Conference · Thu Jan 01 04:00:00 EST 2009

OSTI ID:956523

Chertkov, Michael ^[1]; Chilappagari, Shashi ^[2]; Vasic, Bane ^[2]; Stepanov, Mikhail ^[2]

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1. Los Alamos National Laboratory
2. UNIV OF AZ

We consider linear programming (LP) decoding of a fixed low-density parity-check (LDPC) code over the binary symmetric channel (BSC). The LP decoder fails when it outputs a pseudo-codeword which is not a codeword. We propose an efficient algorithm termed the instanton search algorithm (ISA) which, given a random input, generates a set of flips called the BSC-instanton and prove that: (a) the LP decoder fails for any set of flips with support vector including an instanton; (b) for any input, the algorithm outputs an instanton in the number of steps upper-bounded by twice the number of flips in the input. We obtain the number of unique instantons of different sizes by running the ISA sufficient number of times. We then use the instanton statistics to predict the performance of the LP decoding over the BSC in the error floor region. We also propose an efficient semi-analytical method to predict the performance of LP decoding over a large range of transition probabilities of the BSC.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: DOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 956523
• Report Number(s): LA-UR-09-00307; LA-UR-09-307
• Country of Publication: United States
• Language: English

Related Subjects

97 MATHEMATICS AND COMPUTING
ALGORITHMS
ERRORS
INFORMATION THEORY
INSTANTONS
LINEAR PROGRAMMING
PERFORMANCE
RANGE
STATISTICS
VECTORS