Optimizing Protograph Coded BICM for Half-Duplex DF Relay

Xiaojun SUN
Wei XU
Pengcheng ZHU
Chunming ZHAO

IEICE TRANSACTIONS on Communications   Vol.E95-B    No.4    pp.1397-1401
Publication Date: 2012/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E95.B.1397
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Fundamental Theories for Communications
protograph codes,  LDPC codes,  BICM,  protograph EXIT,  relay,  decode-and-forward,  

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In this letter, we use the the protograph low-density parity check (LDPC) codes to create bit-interleaved coded modulation (BICM) for the half-duplex decode-and-forward (DF) relay network. The DF relay BICM design problem can be transformed into a problem of rate-compatible BICM design, where the different segments of modulated symbols experience different signal-to-noise ratios (SNRs). To optimize the BICM based on the protograph structure, we use the protograph extrinsic information transfer (EXIT) to evaluate the thresholds of different mapping patterns between the variable nodes and the modulated bits. With this tool, we search for the most efficient mapping pattern of BICM for the half-duplex DF relay network. Our work can achieve significant gains over the existing work.