Signal-space characterization of iterative decoding

@article{Frey2001SignalspaceCO,
  title={Signal-space characterization of iterative decoding},
  author={Brendan J. Frey and Ralf Koetter and Alexander Vardy},
  journal={IEEE Trans. Inf. Theory},
  year={2001},
  volume={47},
  pages={766-781}
}
By tracing the flow of computations in the iterative decoders for low-density parity-check codes, we formulate a signal-space view for a finite number of iterations in a finite-length code. On a Gaussian channel, maximum a posteriori (MAP) codeword decoding (or "maximum-likelihood decoding") decodes to the codeword signal that is closest to the channel output in Euclidean distance. In contrast, we show that iterative decoding decodes to the "pseudosignal" that has highest correlation with the… 
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