Title :
High-quality signal transmission techniques for personal communication systems-novel coherent demodulation and ADPCM voice transmission with click noise processing
Author :
Kobayashi, Kaoru ; Sakata, T. ; Matsumoto, Y. ; Enomoto, K. ; Kubota, S. ; Kat, S.
Author_Institution :
NTT Wireless Syst. Labs., Japan
Abstract :
The paper proposes high-quality signal transmission techniques for personal communication systems. A novel coherent demodulator-variable carrier filter and hang-up free clock recovery coherent demodulator (VCHACE)-is proposed. The carrier recovery circuit uses a reverse-modulation scheme with variable bandwidth carrier filter. By employing the proposed scheme, the FER (frame error rate) performance is improved by 2 dB compared with the differential detection scheme in typical Rayleigh fading environments. An ADPCM voice transmission scheme that employs a click noise suppressor is also proposed. It achieves a voice quality improvement of 0.5 points in an MOS evaluation (3 dB improvement in required Eb/No) compared with conventional muting schemes in fading environments
Keywords :
Rayleigh channels; demodulation; demodulators; differential pulse code modulation; fading; personal communication networks; signal processing; voice communication; ADPCM; MOS evaluation; Rayleigh fading; carrier recovery circuit; click noise processing; click noise suppressor; coherent demodulation; coherent demodulator; differential detection; frame error rate performance; hang-up free clock recovery; high quality signal transmission; personal communication systems; reverse modulation; variable bandwidth carrier filter; variable carrier filter; voice quality; voice transmission; Circuits; Clocks; Codecs; Costs; Demodulation; Fading; Filters; Phase change materials; Phase detection; Working environment noise;
Conference_Titel :
Vehicular Technology Conference, 1995 IEEE 45th
Conference_Location :
Chicago, IL
Print_ISBN :
0-7803-2742-X
DOI :
10.1109/VETEC.1995.504965
