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    LDPC Decoding - Error Correction Codes (ECC)

      Ned Varnica
     Nov 6, 2013
    Description:

    LDPC Decoding - Error Correction Codes (ECC) - LDPC Decoding: VLSI Architectures and Implementations. Error Correction Codes (ECC), Intro to Low-density parity-check (LDPC) Codes, ECC Decoders Classification, Soft vs Hard Information, Message Passing Decoding of LDPC Codes, Iterative Code Performance Characteristics. Error Correction Codes (ECC). Error Correcting Codes (ECC). Linear Block Codes. Block Codes, User data is divided into blocks (units) of length K bits/symbols. Each K bit/symbol user block is mapped (encoded) into an N bit/symbol codeword, where N> K. Example:– in Flash Devices user block length K = 2Kbytes or 4Kbytes is typical–code rate R = K / N is usually ~0. 9and higher. Important Linear Block Codes–Reed-Solomon Codes (non-binary)–Bose, Chaudhuri, Hocquenghem (BCH) Codes (binary)–Low Density Parity Check (LDPC) Codes–Turbo-Codes. Generator Matrix and Parity Check Matrix. Low-Density Parity-Check (LDPC) Codes. LDPC Codes - LDPC code is often defined by parity check matrix H, The parity check matrix, H, of an LDPC code with practical length has low density (most entries are 0’s, and only few are 1’s), thus the name, Low-Density, Parity-Check Code, Each bit of an LDPC codeword corresponds to a column of parity check matrix, Each rows of H corresponds to a single parity check, For example, the first row indicates that for any codeword the sum (modulo 2) of bits 0, 1, and N-1must be0. ECC Decoder Classification: Hard vs Soft Decision Decoding. Hard vs. Soft Decoder Classification - Hard decoders only take hard decisions (bits) as the input. E.g. Standard BCH and RS ECC decoding algorithm (Berlekamp-Massey algorithm) is a hard decision decoder. Hard decoder algorithm could be used if one read is available. Hard vs. Soft Decoder Classification. Error-and-Erasure decoder is a variant of soft information decoder: in addition to hard decisions, it takes erasure flag as an input.

    Important Tags: LDPC Decoding, Error Correction Codes, ECC, Free publish electronics presentations
    Views: 6385
    Domain: Electronics
    Category: Semiconductors


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