Bit significance selective frequency diversity transmission-voice quality improvement in fading channels

This paper proposes a frequency diversity transmission scheme that obtains a frequency diversity effect and does not deteriorate spectrum efficiency by utilizing multiple carrier frequencies alternatively, not simultaneously. This scheme improves the bit error rate (BER) or significant information bits by sacrificing that of insignificant bits in fading channels. Simulation results show that the error floor of significant information bits is improved by more than 80% while that of insignificant bits is doubled. Computer simulation results show that the proposed scheme improves the ADPCM voice signal-to noise ratio (SNR) by approximately 4 dB even when the frequency correlation is 0.5. The transmission scheme, TDMA-TDD, can be applied to various types of data transmission in personal communication systems.