Multiple satellite fade attenuation control system

• US 6,587,687 B1
• Filed: 10/21/1996
• Issued: 07/01/2003
• Est. Priority Date: 10/21/1996
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated
• Original Assignee: Globalstar Incorporated
• Inventors: Wiedeman, Robert A.
• Primary Examiner(s): Le, Thanh Cong
• Assistant Examiner(s): Corsaro, Nick
• Application Number:
  US08/734,507
• Time in Patent Office: 2,444 Days
• Field of Search: 455/427, 455/428, 455/429, 455/446, 455/449, 455/450, 455/452, 455/8, 455/10, 455/12.1, 455/13.1, 455/13.4, 455/504, 455/505, 455/63, 455/67.6, 455/67.3
• US Class Current: 455/428
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The teaching of this invention pertains particularly to satellite communications systems using GSO or NGSO satellites. This invention employs data derived from signals of various types to derive a mathematical model of propagation related attenuation-inducing events so as to plan system resource allocation to minimize an amount of power required to close communication links between user terminals and the satellites. Disclosed are methods for modelling gateway to satellite links, as well as methods for modeling the user terminal to satellite links. This invention overcomes the problems inherent in the prior art by providing a direct measurement of severe path attenuation potential. The use of the teaching of this invention enables preplanning of the allocation of satellites and satellite resources by calculating a potential for signal path interference based on an external measurement of where rain attenuation may be located, and the real-time or approximately real-time tracking of rain cell activity within storm cells. Optimization of a global system of satellites is made possible, particularly in the context of a system of LEO satellites.

Claims

1. A method for operating a satellite communications system of a type that includes at least one ground station, at least one satellite, and a plurality of user terminals, comprising the steps of:

generating in substantially real time a model of atmospheric-related, RF signal attenuation-inducing structures located within a coverage area of the ground station; and

allocating at least one of ground station, satellite, and user terminal resources in accordance with the generated model.

2. A method as set forth in claim 1, wherein the step of generating a model includes an initial step of inputting atmospheric-related data from a radar system.

3. A method as set forth in claim 1, wherein the step of generating a model includes an initial step of inputting atmospheric-related data from a satellite observation system.

4. A method as set forth in claim 1, wherein the step of generating a model includes an initial step of generating atmospheric-related data from user terminal signals received by at least one of the ground station and another ground station.

5. A method as set forth in claim 1, wherein the step of generating a model includes a step of generating a three dimensional attenuation contour map of the structures, and a step of updating the contour map so as to reflect the evolution of the structures over time.

6. A method as set forth in claim 1, and further comprising a step of transmitting data indicative of the generated model to a ground station controller, wherein the ground station controller receives data indicative of the generated model from a plurality of ground stations, and wherein the ground station controller allocates satellite communications system resources at least in accordance with the received data.

7. A method as set forth in claim 1, and further comprising a step of transmitting data indicative of the atmospheric-related attenuation-inducing structures to a ground station controller, wherein the ground station controller receives such data from a plurality of ground stations, and wherein the ground station controller generates a global model of RF signal attenuation due to atmospheric effects.

8. A method for managing the power consumption in a satellite communications system of a type that includes at least one ground station, at least one satellite, and a plurality of user terminals, comprising the steps of:

inputting atmospheric-related data from at least one of a radar system and a satellite observation system;

generating in substantially real-time, from the atmospheric-related data, a model of RF signal attenuation-inducing structures located within a coverage area of the ground station; and

assigning at least one of communication links and link powers in accordance with the generated model.

9. A method as set forth in claim 8, wherein the step of generating a model includes an initial step of generating atmospheric-related data from user terminal signals received by at least one of the ground station and another ground station.

10. A method as set forth in claim 8, wherein the step of generating a model includes a step of generating a three dimensional attenuation contour map of the structures, and a step of updating the contour map so as to reflect the evolution of the structures over time.

11. A method as set forth in claim 8, and further comprising a step of transmitting data indicative of the generated model to a ground station controller, wherein the ground station controller receives data indicative of the generated model from a plurality of ground stations, and wherein the ground station controller preemptively allocates satellite communications system resources at least in accordance with the received data.

12. A method as set forth in claim 8, and further comprising a step of transmitting data indicative of the RF signal attenuation-inducing structures to a ground station controller, wherein the ground station controller receives such data from a plurality of ground stations, and wherein the ground station controller generates a global model of RF signal attenuation due to atmospheric effects.

13. A method for operating a satellite communications system of a type that includes a plurality of ground stations, a plurality of satellites, and a plurality of user terminals, comprising the steps of:

at a plurality of the gateways, generating a substantially real time model of atmospheric-related attenuation-inducing structures located within a coverage area of each of the gateways;

transmitting data indicative of the generated model from each of the plurality of gateways to a gateway controller; and

generating gateway commands at the gateway controller for preemptively allocating satellite communications system resources at least in accordance with the received data.

14. A method as set forth in claim 13, and further comprising a step of generating at the gateway controller a global model of RF signal attenuation due to atmospheric effects.

15. A satellite communications system having at least one ground station, at least one satellite, and a plurality of user terminals, said system further comprising a data processor in said ground station for generating a substantially real time model of atmospheric-related RF signal attenuation-inducing structures located within a coverage area of the ground station;

said data processor being further operable for allocating at least one of ground station, satellite, and user terminal resources in accordance with the generated model.

16. A system as set forth in claim 15, wherein the ground station has an input coupled to an output of means for generating atmospheric-related data.

17. A system as set forth in claim 16, wherein said generating means generates the atmospheric-related data from user terminal signals received by at least one of the ground station and another ground station.

18. A system as set forth in claim 15, wherein said processor generates a three dimensional attenuation contour map of the structures.

19. A system as set forth in claim 15, and further comprising a ground station controller that is bidirectionally coupled to said ground station for receiving data indicative of the generated model, wherein said ground station controller receives data indicative of the generated model from a plurality of said ground stations, and wherein the ground station controller comprises control means for generating commands to said plurality of ground stations for allocating satellite communications system resources at least in accordance with the received data.

20. A system as set forth in claim 15, and further comprising a ground station controller that is bidirectionally coupled to said ground station for receiving data indicative of the atmospheric-related RF signal attenuation-inducing structures, wherein said ground station controller receives such data from a plurality of said ground stations, and wherein the ground station controller comprises a data processor for generating a global model of RF signal attenuation due to atmospheric effects.

21. A method for operating a satellite communications system of a type that includes at least one ground station, at least one satellite, and a plurality of user terminals, comprising the steps of:

generating a substantially real time model of atmospheric-related, RF signal attenuation-inducing structures located within a coverage area of the ground station;

determining from a user terminal attenuated RF signal received at the ground station, and in accordance with the generated model, a contribution to the attenuation due to at least two signal propagation effects; and

separately compensating for the at least two effects.

22. A method as set forth in claim 21, wherein a first of the at least two effects is due to RF signal rain attenuation, and wherein a second of the at least two effects is due to RF signal depolarization.

23. A method for operating a satellite communications system of a type that includes at least one ground station, a plurality of satellites, and a plurality of user terminals, comprising the steps of:

generating in substantially real time a current model of atmospheric-related, RF signal impairments located within a coverage area of the ground station; and

allocating at least one of ground station, satellite, and user terminal resources in accordance with the generated model so as to close a communication link between the ground station and a given one of the user terminals with a minimum amount of power consumption.

24. A method as set forth in claim 23, wherein a transmitted power level between the ground station and at least one of the plurality of satellites, and between the at least one of the satellites and the given one of the user terminals, is determined by the ground station.

25. A method as set forth in claim 23, wherein a transmitted power level between the ground station and at least one of the plurality of satellites is determined by the ground station, and wherein a transmitted power level between the at least one of the satellites and the given one of the user terminals is determined by the at least one of the satellites.

26. A method for operating a satellite communications system of a type that includes at least one terrestrial gateway, a plurality of non-geosynchronous orbit satellites that move with respect to a location of the gateway, and a plurality of user terminals located within a coverage area of the gateway, the gateway being bidirectionally coupled to one or more of the user terminals via RF links established through one or more of the satellites, comprising the steps of:

generating data that is descriptive of the presence of a rain cell within the coverage area of the gateway;

deriving from the generated data a three dimensional, substantially real time model of RF signal impairments due to the rain cell; and

allocating system resources so as to compensate for the RF signal impairments as a function of at least a current location of RF signal impairments, a current location of at least one user terminal that is affected by the RF signal impairments, and a current location of one or more of the satellites relative to the current location of the RF signal impairments.

27. A method as in claim 26, wherein the step of generating data also generates an indication of movement of the rain cell, and wherein the step of allocating system resources is further a function of at least one of a predicted future location of the RF signal impairments, and a predicted future location of the one or more satellites.

28. A method as in claim 26, wherein the step of generating data includes a step of operating a radar system for detecting the presence of the rain cell.

29. A method as in claim 26, wherein the step of generating data includes a step of operating an imaging system for detecting the presence of the rain cell.