A Chaos MIMO Transmission Scheme Using Turbo Principle for Secure Channel-Coded Transmission

Eiji OKAMOTO
Yuma INABA

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B    No.8    pp.1482-1491
Publication Date: 2015/08/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.1482
Type of Manuscript: Special Section PAPER (Special Section on 5G Radio Access Networks―Part I: Radio Access Technologies and System Design)
Category: 
Keyword: 
chaos communication,  MIMO,  physical layer security,  log-likelihood ratio,  turbo decoding,  

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Summary: 
Physical layer security is effective in wireless communications because it makes a transmission secure from the beginning of protocols. We have proposed a chaos multiple-input multiple-output (C-MIMO) transmission scheme that achieves both physical layer security and channel coding gain using chaos signals. C-MIMO is a type of encryption modulation and it obtains the coding gain in conjunction with encryption without a decrease in the transmission efficiency. Thus, the error rate performance is improved in C-MIMO. However, decoding complexity increases exponentially with code length because of the use of maximum likelihood sequence estimation (MLSE), which restricts the code length of C-MIMO and thus the channel coding gain. Therefore, in this paper, we consider outer channel code concatenation instead of code length expansion for C-MIMO, and propose an iterative turbo decoding scheme for performance improvement by introducing a log-likelihood ratio (LLR) into C-MIMO and by utilizing turbo principle. The improved performances of the proposed scheme, compared to the conventional scheme when the outer channel codes are convolutional code and low-density parity check (LDPC) code, are shown by computer simulations.