A Frequency Utilization Ffficiency Improvement on Superposed SSMA-QPSK Signal Transmission over High Speed QPSK Signals in Nonlinear Channels

Takatoshi SUGIYAMA
Hiroshi KAZAMA
Shuzo KATO

IEICE TRANSACTIONS on Communications   Vol.E76-B    No.5    pp.480-487
Publication Date: 1993/05/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Satellite Communications Networking and Applications)
SSMA-QPSK signals,  high speed QPSK signals,  superposed transmission,  FEC,  interference cancellation,  non-linear channel,  

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This paper proposes a superposed SSMA (Spread Spectrum Multiple Access)-QPSK (Quadrature Phase Shift Keying) signal transmission scheme over high speed QPSK signals to achieve higher frequency utilization efficiency and to facilitate lower power transmitters for SSMA-QPSK signal transmission. Experimental results show that the proposed scheme which employs the coding-rate of one-half FEC (Forward Error Correction) and a newly proposed co-channel interference cancellation scheme for SSMA-QPSK signals can transmit twenty SSMA-QPSK channels simultaneously over a nonlinearly amplified high speed QPSK signal transmission channel and achieve as ten times SSMA channels transmission as that without co-channel interference cancellation when the SSMA-QPSK signal power to the high speed QPSK signal power ratio equals -30dB. Moreover, cancellation feasibility generation of the interference signals replica through practical hardware implementation is clarified.