Abstract: A system for increasing call-handling capacity employs a multi-tier satellite network which includes one or more geosynchronous (GEO) satellites (12) and non-geosynchronous satellites (14). The GEO satellites (12) transfer non delay-sensitive data through the system, while the non-geosynchronous satellites (14) predominantly transfer delay-sensitive data through the system. In a preferred embodiment, a non-geosynchronous satellite (14) receives (102) a data packet, determines (112) whether or not the data packet is delay-sensitive, routes (114) a delay-sensitive data packet through the LEO network, and routes (116) a non delay-sensitive data packet to a GEO satellite (12).

Abstract: Multiple, different, independent constellations (10, 20) of satellites (2, 21-23) share a portion of a common frequency spectrum such as a single carrier frequency. The satellites' antennas (11) may be either multi-beam or omni-directional, while those of earth stations (13, 14) are directional. When interference occurs between communications of a satellite (31) of a first constellation (10) and a satellite (41) of a second constellation (20), any of several interference-mitigation options may be employed, such as the first satellite (31) handing off communications to a second satellite (32) of the same constellation (10), or temporarily suspending communications. The remedial action may occur in response to either predicted or detected interference.

Abstract: A satellite communication system provides users with global cellular coverage. To facilitate delivery of calls to users having subscriber units, a fixed channel is defined wherein subscriber units are notified of incoming calls. Subscriber units monitor this ring alert channel and examine subscriber unit IDs transmitted in a ring alert message contained therein. When a subscriber unit determines from the subscriber unit ID that a call is being directed to it, it calls into a network to receive a call. Subscriber units also monitor this fixed channel to receive a control channel directory identifying the location of a subscriber unit's broadcast (control) channels.

Abstract: Multiple, different, independent constellations (10, 20) of satellites (2, 21-23) share a portion of a common frequency spectrum such as a single carrier frequency. The satellites' antennas (11) may be either multi-beam or omni-directional, while those of earth stations (13, 14) are directional. When interference occurs between communications of a satellite (31) of a first constellation (10) and a satellite (41) of a second constellation (20), any of several interference-mitigation options may be employed, such as the first satellite (31) handing off communications to a second satellite (32) of the same constellation (10), or temporarily suspending communications. The remedial action may occur in response to either predicted or detected interference.

Abstract: An improved satellite cellular telephone and data communication system facilitates dual satellite coverage over at least eighty-five percent of the earth. This improved system permits communication with hand held and mobile mounted cellular telephones (120). The system permits two-way communications anywhere on or above the earth up to a particular height above the earth of several hundred nautical miles. The system employs a number of low-earth orbiting satellites (12) moving about the earth in orbit. The satellites (12) are inclined at an angle between 30 and 90 degrees. Links (102) are provided from the satellites directly to the users (120) and via the public switched telephone network (20) to other users. The satellites (12) are interconnected via links in a ring structure surrounding the earth. Switching is performed by each of the satellites (12).