Chip-by-Chip Turbo Coding for DS/SS Systems

Chen ZHENG  Takaya YAMAZATO  Masaaki KATAYAMA  Akira OGAWA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.12   pp.2751-2757
Publication Date: 1999/12/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Spread Spectrum Techniques and Applications)
Turbo-codes,  chip-by-chip coding,  DS/SS modulation,  energy compensation,  

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Most of error correcting codes applying to DS/SS systems are such that information data is first (bit-by-bit) encoded and then spread by pseudo noise (PN) sequence. Thus, coding gain achieved by such systems are mainly due to the error correcting codes and the redundancy produced by the spreading codes shows no effect on the coding gain. In this paper, a chip-by-chip Turbo coding for DS/SS systems is proposed. The input information data is first spread by PN sequence and then fed into the Turbo-encoder which operates in chip timing. As the Turbo-encoder operates in chip timing, a large interleaving size would be obtained, which improves the performance. As results, superior performances with coding gain of more than 3.0 dB and 5.0 dB for AWGN and Rayleigh-fading channel, respectively, were found with short frame size of information data.