Effect on total system capacity due to imperfect power control forband sharing between CDMA based non-geostationary satellite-PCNs

摘要

The demand for global telephony services for mobile users requiresthe use of constellations of non-geostationary orbits. The proposedS-PCNs are Iridium, Inmarsat-P, Globalstar, Odyssey and Ellipso. Thefirst two systems propose to use a time division multiple access (TDMA)scheme and the others code division multiple access (CDMA) scheme. It isclaimed that CDMA based S-PCNs can share the allocated frequency bandsdue to the interference resistant property of CDMA. Spectrum sharingmust be based on defined interference criteria being satisfied. Theinterference events are based on the statistics of carrier tointerference ratio (C/I). For this a computer simulation was developedto model the dynamic nature of any constellation, and produces all thestatistical values of C/I to a mobile in a fading channel. Thesimulation includes constellations results of proposed S-PCNs withmulti-spotbeam antennas (MBA). We present the results of theinvestigation on the effect of imperfect power control on the totalsystem capacity for a totally overlapped band sharing scenario. Resultsfor a band segmented scenario are also presented for comparison