Power control versus capacity of a CDMA system operating over a low Earth orbiting satellite link

Low Earth orbiting satellite (LEOS) communications suffer from the shadowing effects of trees and buildings on both the up-link and the down-link. The shadowed user link to the satellite experiences Rayleigh fading. To combat this, power control is employed, as well as coding and diversity. The authors derive an analytical expression for the total capacity degradation of both up-link and down-link under the constraint of limited satellite power (or power flux density). The down-link in particular suffers from the shadowed users because of the increase in transmit power to accommodate the shadowed user. This, in turn, “robs” power from the non-shadowed user