Title :
Improved ADPCM voice signal transmission employing click-noise detection scheme for TDMA-TDD personal communication systems
Author :
Kubota, Shuji ; Dobashi, Akira ; Suzuki, Masanobu ; Hasumi, Takeo ; Kato, Shuzo
Author_Institution :
NTT Wireless Syst. Labs., Yokosuka, Japan
fDate :
2/1/1997 12:00:00 AM
Abstract :
In personal communication systems, better voice quality and lower terminal price are essential requirements, and adaptive differential pulse-code modulation (ADPCM) codecs are one of the voice codec candidates that have good voice quality and reasonable cost. However, in slow fading environments, burst errors induce click noise in ADPCM voice signal transmission. This paper proposes a novel error-concealment scheme to improve the ADPCM voice signal transmission quality of time division multiple access time division duplex (TDMA-TDD) personal communication systems in slow fading environments. The proposed scheme employs an improved error-detection technique with PCM differential detection and overflow detection coupled with a cyclic redundancy check (CRC) code. To compensate for residual click noise, an expanded CRC error-detection signal is used. Erroneous PCM signals are adaptively suppressed according to the click-noise detection information. Hardware simulation results show that these techniques significantly improve ADPCM voice signal transmission quality by 0.5 points and 1.0 compared to that of the conventional ADPCM muting scheme and no processing, respectively, with the mean opinion scoring (MOS) test in the slow fading environments typical of personal communication systems
Keywords :
codecs; cyclic codes; demodulation; differential pulse code modulation; error correction; error detection codes; fading; noise; personal communication networks; speech codecs; time division multiple access; voice communication; ADPCM codecs; ADPCM muting; ADPCM voice signal transmission; PCM differential detection; TDMA-TDD; adaptive differential pulse-code modulation; burst errors; click-noise detection; cyclic redundancy check code; error concealment; error detection; expanded CRC error-detection signal; hardware simulation results; mean opinion scoring test; overflow detection; personal communication systems; personal terminal; slow fading environments; time division duplex; time division multiple access; voice codec; voice quality; Codecs; Costs; Couplings; Cyclic redundancy check; Fading; Modulation coding; Phase change materials; Pulse modulation; Time division multiple access; Working environment noise;
Journal_Title :
Vehicular Technology, IEEE Transactions on
