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EXIT Charts Analysis for Turbo-TCM Schemes Using Non-Binary RSC Encoders

Authors:
Calin Vladeanu
Alexandru Martian
Safwan El Assad

Keywords: EXIT charts; GF(2^N)encoders; Punctured Turbo TCM; Symbol-by-Symbol log-MAP; LCIRC

Abstract:
Recently, a new family of recursive systematic convolutional (RSC) encoders over Galois field GF(2^N) was introduced. The present paper considers the parallel turbo trellis coded modulation (TTCM) scheme using these nonbinary encoders as constituent codes. Besides operating over a higher order Galois field, these encoders use a non-linear function, the left-circulate (LCIRC) function, to control the encoder states. It is shown that these rate-(N-1)/N GF(2^N) RSC-LCIRC encoders offer the same performances in terms of minimum Euclidian distance, effective length, and product distance, as compared to corresponding binary encoders. Moreover, these RSC-LCIRC encoders are requiring less memory usage. Extrinsic information transfer (EXIT) charts are used to analyze the convergence of the proposed punctured TTCM schemes, with 8-PSK and 16-QAM modulations, symbol-bysymbol log-MAP decoding algorithm, when transmitting over AWGN and Rayleigh non-selective fading channels. EXIT charts show some improvements in terms of TTCM decoding schemes convergence for the RSC-LCIRC codes as compared to their binary counterparts.

Pages: 150 to 155

Copyright: Copyright (c) IARIA, 2012

Publication date: May 27, 2012

Published in: conference

ISSN: 2308-4030

ISBN: 978-1-61208-199-1

Location: Stuttgart, Germany

Dates: from May 27, 2012 to June 1, 2012