Fully interconnected spot beam satellite communication system

DETAILED DESCRIPTION The system of the present invention relates to a satellite communications system in which an earth station in any one spot beam coverage area can communicate to an earth station in the same or any other spot beam coverage area without a large number of transponders or active switching in the satellite.
Each uplink signal received by a satellite from a spot beam coverage area is routed to a single specific downlink spot beam depending on the carrier frequency involved.
The routing technique can be characterized by a frequency-selective routing array (FSRA) in the satellite.
The signal is routed by assigning to the earth stations at each end of a communications link an appropriate uplink frequency (F.
sub.
N) that will result in the correct routing.
A network control center (NCC) located on the ground in one of the spot beam coverage areas receives signalling requests and assigns frequencies so that the desired route will be established.
This use of a NCC on the ground and a FSRA in the satellite is referred to as frequency assigned switching (FAS).
Using spot beams also allows the reuse of frequencies, thereby enlarging the total potential capacity of a single satellite orbit position.
If a frequency spectrum is used in area A, and area A is geographically remote from area B, that same frequency spectrum may also be used in area B.
This, of course, will increase the total bandwidth available for transmission of signals beyond that which is possible in a single beam system.
Accordingly, it is an object of the present invention to provide an improved communication system.
It is another object of the present invention to provide a spot beam satellite communication system that is fully interconnected without using active switching in the satellite and without the need for N.
sup.
2 transponders where N is the number of spot beam coverage areas.
It is another object of the invention to provide a satellite communication system wherein higher effective isotropically radiated power is obtained over a wide geographic coverage area by use of multiple spot beams and low-power amplifiers such that total satellite power is not increased and interconnectivity among all points of the coverage area is maintained