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On Iterative Decoding Of Two-Level Superposition Codes For Cooperative Broadcasting Based On Qpsk And 4-Pam Constellations, Robert H. Morelos-Zaragoza
On Iterative Decoding Of Two-Level Superposition Codes For Cooperative Broadcasting Based On Qpsk And 4-Pam Constellations, Robert H. Morelos-Zaragoza
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This paper considers iterative decoding of two-level superposition codes used in cooperative broadcasting over wireless networks. The coding scheme consists of two low-density parity-check (LDPC) codes combined using Plotkin's |u|u + v|-construction and provides two levels of error protection. Coding for cooperative broadcasting differs from conventional single-source broadcast coding. Instead of binary addition of subcode codewords performed by a single-source encoder, in superposition coding two modulated subcode sequences, produced by two coordinated and independent sources, are combined at the antenna of the receiver. Expressions are derived for the bit metrics, or log-likelihood ratio values, used by an iterative decoder for …