Satellite link margin and availability issues are addressed in this paper. Typical sources of disputes in satellite link design results generated by different satellite link engineers are described and solutions to resolve the disputes are proposed. The solutions include provision of accurate and simplified methods with mathematical derivation support to estimate the availabilities of satellite links due to rainfall for a specified transponder power utilization. Derivation and description of the link availability methods are provided for one-way (simplex) link and two-way (duplex) link, with or without the use of uplink power control at the transmit station, and for the general case where uplink and downlink rain is uncorrelated (e.g., transmit and receive stations are very far from each other) as well as the specific case where the rain is completely correlated (e.g., transmit and receive stations are the same or very close each other). The accurate methods are based on the use of discrete probability density functions of uplink and downlink rain attenuations which are readily available from any existing rain attenuation models. The simplified methods are provided to further simplify the computation involved. Comparison between the methods is also performed.
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