Method for limiting interference between satellite communications systems

• US 6,511,020 B2
• Filed: 01/05/2001
• Issued: 01/28/2003
• Est. Priority Date: 01/07/2000
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Higgins, Robert P.
• Primary Examiner(s): Jordan, Charles T.
• Assistant Examiner(s): Holzen, Stephen A
• Application Number:
  US09/755,655
• Publication Number:
  US 20010045494A1
• Time in Patent Office: 753 Days
• Field of Search: 244/158.R, 244/159, 244/173
• US Class Current: 455/12.1
• CPC Class Codes: B64G 1/1007 Communications satellites
• CPC Class Codes: B64G 1/1085 Swarms and constellations
• CPC Class Codes: B64G 1/242 Orbits and trajectories
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/195 Non-synchronous stations

Abstract

Boeing achieves satellite diversity by having a large discrimination angle for a MEO constellation of communications satellites to limit interference in the Ku-band with GSO communications systems. Each satellite entering an exclusion zone over a GSO ground station terminates all transmissions to provide EPFD within acceptable limits. The Boeing MEO constellation preferably comprises 20 satellites, 5 in each orbit. The four orbits are inclined at about 57° with respect to the equator. Services include an Integrated Digital Service (IDS) and Backhaul Data Service (BDS) to accommodate the needs of different users.

Claims

1. A communication satellite particularly adapted for use in a MEO satellite constellation and system for full service, global communication or communication (voice) and data signals, comprising:

(a) a platform;

(b) at least two transceivers on the platform for receiving and transmitting of the signals, each transceiver including Integrated Digital Service (IDS) and Backhaul Data Service (BDS) for transmission, each transceiver also having a feeder link antenna and a tracking control system adapted for pointing and tracking the feeder link antenna at a selected gateway on the Earth,

wherein seamless handoff between gateways occurs because each feeder link antenna has its own, dedicated tracking control system to allow each antenna to point at a different, selected gateway,

wherein the IDS includes an antenna that generates a pattern of spot beams to communicate with a plurality of user terminals with each spot beam having a three-cell frequency reuse pattern and dual polarization to provide a spectrum reuse factor in excess of 24, and

wherein the BDS has a plurality of paired, steerable transmit and receive beams with forward links employing time division multiplexed (TDM) channels, each channel carrying a 24.4 Mb/s information-stream, and with return links employing a bent-pipe transponder to provide high speed transfer up to 120 Mb/s.

2. The satellite of claim 1 wherein the BDS uses a multi-beam electronically steered phased array antenna.

3. The satellite of claim 1, wherein the IDS system further comprises, for the transmitter, an encoder/modulator paired with a power amplifier for providing a transmission signal to each beam, each encoder/modulator also being coupled with a common switch for all encoder/modulator pairs and wherein the BDS system further comprises a filter network coupled with a plurality of frequency translators, each frequency translator coupled with an exciter for providing a transmission signal to a multibeam transmit phased array antenna.

4. The satellite of claim 1 wherein the IDS uses a “

bit container”

transmission structure.

5. The satellite of claim 1 wherein the BDS channels have a bandwidth of 58.7 MHz and the BDS uses a carrier spacing of 68.5 MHz.

6. The satellite of claim 4 wherein the BDS channels have a bandwidth of 58.7 MHz and the BDS uses a carrier spacing of 68.5 MHz.

7. The satellite of claim 1 wherein the transmissions use a combination of single polarization and dual-circular polarization.

8. The satellite of claim 4 wherein the transmissions use a combination of single polarization and dual-circular polarization.