Composition of iridium star

Iridium is mainly composed of the following parts: satellite constellation, ground control facilities, gateway stations and user terminals (voice, data and fax). Each star can provide 48 (originally designed as 37) spot beams, each beam contains 80 channels on average, and each star can provide 3840 full-duplex circuit channels. Each star uses interplanetary cross links as networking means, including forward-looking and backward-looking links connecting two adjacent stars in the same orbital plane, and two links with satellites in different orbits. The system has the functions of space exchange and routing. The system adopts "inverted" honeycomb structure. The multi-beam projected by each star forms 48 honeycomb areas on the earth's surface, each with a diameter of about 667KM. They are combined with each other, with a total coverage diameter of about 4000KM, and there are 2 150 communities in the world. The system adopts seven-cell frequency reuse method, and any two cells using the same frequency are separated by two buffer cells, which can

The basic structure and treatment of iridium satellites are all on board, and the honeycomb area quickly sweeps across the earth's surface with the rotation of the earth. The handover of iridium satellite system is that the cells move across users, not users move across cells, which is different from the future public land mobile telecommunication system. Iridium system costs about $3.4 billion. It was first published in June 1990. 1990 applied for a license from the FCC of the United States in February, and obtained the license from the FCC in September 1992. At that time, iridium satellite system was the most complete and concrete design scheme, which made rapid progress and was a very promising scheme. Unfortunately, due to various reasons, the Iridium system fell short and declared bankruptcy.