Decoding of Expander Codes at Rates Close to Capacity

dc.creatorAshikhmin, Alexei
dc.creatorSkachek, Vitaly
dc.date2005-08-12
dc.date2007-01-22
dc.date.accessioned2026-07-07T08:15:34Z
dc.date.available2026-07-07T08:15:34Z
dc.descriptionThe decoding error probability of codes is studied as a function of their block length. It is shown that the existence of codes with a polynomially small decoding error probability implies the existence of codes with an exponentially small decoding error probability. Specifically, it is assumed that there exists a family of codes of length N and rate R=(1-ε)C (C is a capacity of a binary symmetric channel), whose decoding probability decreases polynomially in 1/N. It is shown that if the decoding probability decreases sufficiently fast, but still only polynomially fast in 1/N, then there exists another such family of codes whose decoding error probability decreases exponentially fast in N. Moreover, if the decoding time complexity of the assumed family of codes is polynomial in N and 1/ε, then the decoding time complexity of the presented family is linear in N and polynomial in 1/ε. These codes are compared to the recently presented codes of Barg and Zemor, ``Error Exponents of Expander Codes,'' IEEE Trans. Inform. Theory, 2002, and ``Concatenated Codes: Serial and Parallel,'' IEEE Trans. Inform. Theory, 2005. It is shown that the latter families can not be tuned to have exponentially decaying (in N) error probability, and at the same time to have decoding time complexity linear in N and polynomial in 1/ε.
dc.descriptionAppears in IEEE Transactions on Information Theory, December 2006. The short version of this paper appears in the proceedings of the 2005 IEEE International Symposium on Information Theory, Adelaide, Australia, September 4-9, 2005
dc.identifierhttps://arxiv.org/abs/cs/0508062
dc.identifierhttp://arxiv.org/abs/cs/0508062
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/133489
dc.subjectInformation Theory
dc.titleDecoding of Expander Codes at Rates Close to Capacity
dc.typetext

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