SSMA and spread FDMA transmission through a nonlinear satellite channel

The authors analyze and compare two possible access schemes, spread-spectrum multiple access (SSMA) and frequency-division multiple access (FDMA) to be used in satellite networks with a large number of small users. For FDMA, it is assumed that individual carriers are also spread, to the extent that the available bandwidth is always fully occupied. Spectral efficiencies are computed and compared for transmission through a nonlinear satellite channel in the presence of thermal noise and external interference, in addition to the self-interference that is intrinsic to the SSMA system. Optimum operating points for the nonlinear amplifier are also determined. As for the linear channel, spread FDMA shows higher efficiency than SSMA for the nonlinear channel.<
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