Two-User Turbo Decoding with Simplified Sum Trellis in Two-Way Relay Channel

Shan LU  Jun CHENG  Ying LI  Yoichiro WATANABE  

IEICE TRANSACTIONS on Communications   Vol.E96-B   No.1   pp.73-80
Publication Date: 2013/01/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E96.B.73
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Fundamental Theories for Communications
two-way relay channel,  physical-layer network coding,  turbo decoding,  sum trellis,  

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Physical-layer network coding with binary turbo coding in a two-way relay channel is considered. A two-user turbo decoding scheme is proposed with a simplified sum trellis. For two-user iterative decoding at a relay, the component decoder with its simplified sum trellis decodes the superimposed signal to the arithmetic sum of two users' messages. The simplified sum trellis is obtained by removing one of the states in a pair of mutual symmetrical states from a sum trellis. This removal reduces the decoding complexity to half of that with the sum trellis, and does not degrade decoding performance over AWGN channel since two output sequences from the pair of mutual symmetrical states are the same.