Title :
Bit-stream-arranged weighted modulation scheme for frequency selective fading channels
Author :
Kobayashi, Kiyoshi ; Kubota, Shuji
Author_Institution :
NTT Wireless Syst. Labs., Kanagawa, Japan
Abstract :
This paper proposes a bit-stream-arranged weighted modulation scheme to improve the voice quality in frequency selective fading channels. The proposed modulation scheme employs an input bit stream arrangement method which changes the bit stream order for important bits so that they do not adjoin each other over time and a mapping method which controls the amplitude of modulation signals according to the importance of the bits. Computer simulations clarify that the proposed bit-stream-arranged weighted modulation scheme shows a noise reduction of 7 dB in voice signal compared with the conventional π/4 shift DQPSK modulation scheme
Keywords :
encoding; fading; pulse code modulation; speech coding; speech intelligibility; voice communication; π/4 shift DQPSK modulation; BER; PCM; bit stream arranged weighted modulation; bit stream order; computer simulations; differential encoder; frequency selective fading channels; input bit stream arrangement method; mapping method; modulation signal amplitude control; noise reduction; voice quality; AWGN; Amplitude modulation; Bit error rate; Degradation; Delay; Equalizers; Fading; Frequency modulation; Phase change materials; Pulse modulation;
Conference_Titel :
Global Telecommunications Conference, 1996. GLOBECOM '96. 'Communications: The Key to Global Prosperity
Conference_Location :
London
Print_ISBN :
0-7803-3336-5
DOI :
10.1109/GLOCOM.1996.587644
