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Generalized Product Accumulate Codes:
Analysis and Performance
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GLOBECOM 2001
San Antonio
Nov., 2001
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J.Li,
K.R.Narayanan, C.N.Georghades
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[pdf]
Abstract --
In [1][2], product accumulate (PA) codes were
proposed and shown to be a class of simple and provably good codes for rate R<=1/2. This work investigates the generalized product accumulate (GPA) codes
which have rates over the entire range and which are also "good" both in the
maximum likelihood (ML) sense and under the iterative approach. Analysis
concentrates on the weight distribution over the code ensemble,
the ML bounds,
and the existence and computation of threshold phenomenon in the iterative
decoding. A tight upper bound due to Divsalar and the thresholds computed using density
evolution are examined. Simulations are presented and evaluated, especially for rate R<=1/2.
Keywords --
product accumulate codes, generalized product accumulate codes,
serial / parallel concatenation,
turbo product codes, repeat accumulate codes,
Tanner graph, density evolution, union bounds, Galager bounds, Divsalar bounds,
interleaving gain, message-passing decoding,
sum-product decoding,
min-sum decoding
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