Bit Significance Selective Frequency Diversity Transmission

Tomoaki KUMAGAI  Kiyoshi KOBAYASHI  Katsuhiko KAWAZOE  Shuji KUBOTA  

IEICE TRANSACTIONS on Communications   Vol.E81-B   No.3   pp.545-552
Publication Date: 1998/03/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Communication Theory
frequency diversity,  spectrum efficiency,  fading,  ADPCM,  

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This paper proposes a frequency diversity transmission scheme that obtains a frequency diversity gain and does not degrade spectrum efficiency; it utilizes multiple carrier frequencies alternately, not simultaneously. This scheme improves the bit error rate (BER) of significant information bits by sacrificing that of insignificant bits in fading channels. Simulation results show that the error floor of significant information bits is reduced to less than 1/5 while that of insignificant bits is doubled. They also show that the proposed scheme improves the received 4-bit ADPCM voice signal-to-noise ratio (SNR) by approximately 4 dB even when the frequency correlation is 0. 5.