Performance Evaluation of Symbol-Wise XOR Based Bi-directional Relaying

Jianming WU  Shunji MIYAZAKI  Kazuhisa OHBUCHI  Tomohiko TANIGUCHI  

IEICE TRANSACTIONS on Communications   Vol.E92-B    No.5    pp.1796-1807
Publication Date: 2009/05/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.1796
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Radio Access Techniques for 3G Evolution)
DF,  AF,  bi-directional relaying,  XOR,  redundant MCS,  repetition coding,  

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In this paper, we investigate the system performance of decode and forward based bi-directional relaying based on symbol-wise XOR operation. This technique gives more freedom in selecting the modulation and coding scheme at relay stations, and significantly relaxes the transmission bottleneck. However, the performance degradation occurs when the modulation orders of both links differ from each other. To mitigate such an impact, we exploit a repetition coding scheme in conjunction with a redundant modulation code scheme by overlapping MCS levels. To this end, a system level simulation proves that the proposed scheme achieves about 43% capacity gain over bit-wise XOR based bi-directional relaying and gives additional 10% gain over symbol-wise XOR based bi-directional relaying.