The Iridium satellite communication system was designed with a link margin of 16 dB, and was originally advertised as being capable of providing service to users with hand-held phones in vehicles, buildings, and urban areas. Today, after bankruptcy and restructuring of the company, it is recommended that Iridium phones be used outdoors, with a line of sight to the satellites. Find some estimates of the link margins (due to fading) required for L-band communications into vehicles and buildings. Do you think the Iridium system would have operated reliably in these environments? If not, why was the system designed with a 16 dB link margin?