Satellite communication system with a plurality of limited scan spot beams
First Claim
1. In a satellite communication system, an on-board satellite switching subsystem comprising:
- a plurality of x scannable receiving antenna ports (121 -12x), each receiving antenna port being associated with a separate one of x possible up-link beams (101 -10N) and only n of x beams are concurrently receivable at any instant of time, where n≦
x, each up-link beam being capable of propagating bursts of information in a predetermined time division multiple access (TDMA) sequence during a system frame period from a predetermined number of a plurality of m spaced-apart ground areas forming an overall system service region to the associated scannable receiving antenna port, where n≦
m and different traffic demands exist between each of the pairs of the m ground areas;
a plurality of x scannable transmitting antenna ports (161 -16x), each transmitting antenna port being capable of forming a separate scannable down-link spot beam and the x scannable transmitting antenna ports are capable of transmitting the bursts of information concurrently received at the n of x scannable receiving antenna ports at any instant of time toward the destined ground areas in appropriate n of x concurrently transmitted down-link beams in accordance with said predetermined TDMA sequence; and
switching means (34) disposed between the plurality of x scannable receiving antenna ports and the plurality of x scannable transmitting antenna ports and capable of selectively transferring the n bursts of information concurrently received at the receiving antenna ports at any instant of time to the appropriate transmitting antenna ports in accordance with said predetermined TDMA sequence for appropriate transmission in the n of x concurrently transmitted down-link beams to the destined ground areas;
characterized in thatthe x antenna ports of each of the plurality of scannable receiving and transmitting antenna ports are each scannable over only a separate limited portion of the plurality of m ground areas forming the overall system service region and are formed into n groups of one or more antenna ports, each group of receiving and transmitting antenna ports being associated with a separate one of the n concurrently received and transmitted beams, respectively, in a manner so that each group of receiving and transmitting antenna ports handles the traffic requirements of a separate one of n limited non-interfering transmitting communication zones (S1 -SN) and n limited non-interfering receiving communication zones (R1 -RN), respectively, and each of said limited non-interfering transmitting and receiving communication zones comprises a substantially equal traffic requirement.
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Abstract
The present invention relates to a satellite communication system comprising a plurality of limited scan spot beams which permits high transponder utilization efficiency by virtue of pooling the resources of each terrestrial footprint. In an embodiment of the invention, a satellite comprises a plurality of transponders, the signals from each transponder being directed via one or more associated scanning beams over a separate limited scanning beam region on the surface of a celestial body. In a preferred arrangement, each of the plurality of scanning spot beams is scanned linearly and parallel to the other scanning spot beams in a manner wherein each of the scanning beams covers a separate one of adjacent bands dividing the overall service region on the celestial body. By proper orientation of each of the scan regions or bands, nearly equal volumes of traffic can be served by each transponder.
60 Citations
6 Claims
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1. In a satellite communication system, an on-board satellite switching subsystem comprising:
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a plurality of x scannable receiving antenna ports (121 -12x), each receiving antenna port being associated with a separate one of x possible up-link beams (101 -10N) and only n of x beams are concurrently receivable at any instant of time, where n≦
x, each up-link beam being capable of propagating bursts of information in a predetermined time division multiple access (TDMA) sequence during a system frame period from a predetermined number of a plurality of m spaced-apart ground areas forming an overall system service region to the associated scannable receiving antenna port, where n≦
m and different traffic demands exist between each of the pairs of the m ground areas;a plurality of x scannable transmitting antenna ports (161 -16x), each transmitting antenna port being capable of forming a separate scannable down-link spot beam and the x scannable transmitting antenna ports are capable of transmitting the bursts of information concurrently received at the n of x scannable receiving antenna ports at any instant of time toward the destined ground areas in appropriate n of x concurrently transmitted down-link beams in accordance with said predetermined TDMA sequence; and switching means (34) disposed between the plurality of x scannable receiving antenna ports and the plurality of x scannable transmitting antenna ports and capable of selectively transferring the n bursts of information concurrently received at the receiving antenna ports at any instant of time to the appropriate transmitting antenna ports in accordance with said predetermined TDMA sequence for appropriate transmission in the n of x concurrently transmitted down-link beams to the destined ground areas; characterized in that the x antenna ports of each of the plurality of scannable receiving and transmitting antenna ports are each scannable over only a separate limited portion of the plurality of m ground areas forming the overall system service region and are formed into n groups of one or more antenna ports, each group of receiving and transmitting antenna ports being associated with a separate one of the n concurrently received and transmitted beams, respectively, in a manner so that each group of receiving and transmitting antenna ports handles the traffic requirements of a separate one of n limited non-interfering transmitting communication zones (S1 -SN) and n limited non-interfering receiving communication zones (R1 -RN), respectively, and each of said limited non-interfering transmitting and receiving communication zones comprises a substantially equal traffic requirement. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification