Title :
Improved efficiency CDMA by constant envelope SQAM
Author :
Wan, Zhen ; Feher, Kamilo
Author_Institution :
Dept. of Electr. & Comput. Eng., California Univ., Davis, CA, USA
Abstract :
In order to reduce the interference into the adjacent channel and to increase the processing gain of the CDMA system, a power and spectral efficient superposed-quadrature-amplitude-modulation code-division-multiple-access (SQAM-CDMA) system is proposed. In the hard-limited power amplified channel, SQAM-CDMA has about 12-16 dB lower out-of-band power interference into the adjacent channel than that of QPSK-CDMA, and 11-15 dB lower than that of BPSK-CDMA. Assuming a 30 dB lower out-of-band interference power is required in a given RF bandwidth, the processing gain of SQAM-CDMA is increased by 7 dB over QPSK-CDMA and 9.5 dB over BPSK-CDMA in the hard-limited amplified channel
Keywords :
amplitude modulation; code division multiple access; interference suppression; mobile radio systems; spread spectrum communication; CDMA; adjacent channel interference reduction; constant envelope SQAM; efficiency; hard-limited power amplified channel; mobile communications; processing gain; spread spectrum communication; superposed-quadrature-amplitude-modulation code-division-multiple-access; Bandwidth; Baseband; Demodulation; High power amplifiers; Low pass filters; Multiaccess communication; Radio frequency; Radiofrequency interference; Robustness; Signal processing;
Conference_Titel :
Vehicular Technology Conference, 1992, IEEE 42nd
Conference_Location :
Denver, CO
Print_ISBN :
0-7803-0673-2
DOI :
10.1109/VETEC.1992.245399
