Satellite repeater diversity resource management system

• US 6,654,357 B1
• Filed: 06/25/1998
• Issued: 11/25/2003
• Est. Priority Date: 06/06/1995
• Status: Expired due to Fees

• Current Assignee: Globalstar Incorporated
• Original Assignee: Globalstar Incorporated
• Inventors: Wiedeman, Robert A.
• Primary Examiner(s): Holloway, III, Edwin C.
• Application Number:
  US09/104,712
• Time in Patent Office: 1,979 Days
• Field of Search: 370/315, 370/328, 370/18, 370/316, 375/267, 375/137, 375/211, 455/13.1, 455/13.3, 455/13.4, 340/7.2
• US Class Current: 370/315
• CPC Class Codes: H04B 7/18534 for enhancing link reliablility, e.g. satellites diversity
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A satellite communications system (10) has a controller for improving and optimizing the delivery of path diversity in a satellite repeater-based communication system, thereby conserving both FDM channels and satellite power utilization. The reception of communications is improved, when one or more orbiting satellite repeater (12) transmitters is blocked or severely faded, by recognizing the need for satellite path diversity on a real-time or near real-time basis. A user terminal (13) is thus enabled to receive sufficient signal strength to avoid having an ongoing call automatically terminated. The system optimizes satellite path diversity applied to (a) classes (types) of user terminals and/or (b) to individual user terminals as a function of location and also a local RF propagation environment of the user terminal. In addition, a consideration is made of the satellite resources that are available at any given point in time, and may restrict or limit the availability of satellite path diversity, thereby increasing overall system capacity.

Claims

1. A communications system, comprising:

a plurality of communication signal repeaters;

a communication signal transmitter having a plurality of antennas for selectively transmitting a communication signal to individual ones of said communication signal repeaters;

a communication signal receiver for receiving a communication signal from said communication signal transmitter through at least one of said communication signal repeaters, said communication signal receiver being one of a plurality of types of communication signal receiver, said plurality of types comprising at least a fixed communication signal receiver and a mobile communication signal receiver; and

control means, responsive to information specifying at least what type said communication signal receiver is, for specifying a number of said communication signal repeaters to be used in repeating a communication signal that is transmitted from said communication signal transmitter to said communication signal receiver.

2. A communication system as set forth in claim 1 wherein said control means is further responsive to information that specifies a location of said communication signal receiver for specifying the number of said communication signal repeaters to be used in repeating the communication signal that is transmitted from said communication signal transmitter to said communication signal receiver.

3. A communication system as set forth in claim 1 wherein said control means is further responsive to information that specifies an RF propagation environment of said communication signal receiver for specifying the number of said communication signal repeaters to be used in repeating the communication signal that is transmitted from said communication signal transmitter to said communication signal receiver.

4. A communication system as set forth in claim 1 wherein said control means is further responsive to information that specifies a historical usage of the system by the communication signal receiver for specifying the number of said communication signal repeaters to be used in repeating the communication signal that is transmitted from said communication signal transmitter to said communication signal receiver.

5. A communication system as set forth in claim 1 wherein said communication signal receiver is a component of a transceiver having a transmitter that is remotely power controlled, and wherein said control means is further responsive to information specifying a power control history for said transmitter of said transceiver for specifying the number of said communication signal repeaters to be used in repeating the communication signal that is transmitted from said communication signal transmitter to said communication signal receiver.

6. A system as set forth in claim 2 wherein the information specifying a location of said communication signal receiver includes information that specifies an RF energy propagation characteristic that is associated with an environment within which the communications signal receiver is located.

7. A system as set forth in claim 1 wherein said plurality of communication signal repeaters are comprised of a plurality of earth orbiting satellites.

8. A system as set forth in claim 7 wherein said plurality of earth orbiting satellites form a portion of a constellation of low earth orbit (LEO) satellites.

9. A communication system as set forth in claim 7 wherein said control means is further responsive to information that specifies a current availability of said plurality of earth orbiting satellites for specifying the number of said communication signal repeaters to be used in repeating the communication signal that is transmitted from said communication signal transmitter to said communication signal receiver.

10. A method of operating a satellite communication system, comprising the steps of:

initiating a communication between a user terminal and a ground station via at least one satellite communication signal repeater;

classifying the user terminal as to a type of user terminal, wherein types of user terminals comprise at least a fixed user terminal and a mobile user terminal; and

selecting a number of satellite communication signal repeaters to relay the communication between the user terminal and the ground station, the selected number being a function of at least the type of the user terminal.

11. A method as set forth in claim 10 wherein the step of selecting further includes a step of determining a location of the user terminal within an area serviced by the ground station.

12. A method as set forth in claim 11 wherein the step of selecting includes a step of determining an RF energy propagation characteristic that is associated with the determined location of the user terminal.

13. A method as set forth in claim 10 wherein the step of selecting includes a step of considering a power control history of the user terminal.

14. A method as set forth in claim 10 wherein the step of selecting includes a step of considering a system usage history of the user terminal.

15. A method as set forth in claim 10 wherein the step of selecting includes a step of considering an availability of satellite communication signal repeaters.

16. A method as set forth in claim 10 wherein the communication is bidirectionally relayed as a spread spectrum, code division multiple access communication signal between the user terminal and the ground station.

17. A method as set forth in claim 10 and further comprising the steps of:

receiving the communication with the user terminal, the communication being received through different communication paths associated with individual ones of the selected number of satellite communication signal repeaters;

equalizing at least the phase shifts and delays of the received communication from each of the different paths to provide a plurality of equalized communication signals; and

combining the equalized communication signals into a composite received communication signal.

18. A satellite communication system, comprising:

a plurality of communication satellites;

a ground station having a transceiver for transmitting and receiving communication signals with said plurality of communication satellites;

a user terminal having a transceiver for transmitting and receiving communication signals with said plurality of communication satellites;

said ground station further having a data base of user terminal-related information including information specifying a type of said user terminal, wherein said type is selected from the group consisting of a fixed user terminal and a mobile user terminal, said data base further storing information that is descriptive of an RF propagation characteristic of a region within a service area of said ground station;

said ground station further having control means that is coupled to said data base and to a rules set for determining a number of said plurality of communication satellites for relaying a communication between said user terminal and said ground station, said ground station including means for determining a location of said user terminal, and wherein said control means determines the number of communication satellites in accordance with said user terminal type, said location of said user terminal, and an RF propagation characteristic that is associated with said location of said user terminal.

19. A satellite communication system as set forth in claim 18, wherein said data base further stores information that is descriptive of user terminal historical power control activity.

20. A satellite communication system as set forth in claim 18, wherein said data base further stores information that is descriptive of user terminal historical system usage.

21. A satellite communication system as set forth in claim 18, wherein said plurality of communication satellites comprise a Walker constellation of low earth orbit satellites, and wherein communications are bidirectionally transmitted as spread spectrum, code division multiple access communication signals between a user terminal'"'"'s transceiver and the ground station'"'"'s transceiver, through at least one of said plurality of communication satellites.

22. A method of operating a satellite communication system, comprising the steps of:

initiating a communication between a user terminal and a ground station via at least one satellite communication signal repeater;

determining, at the ground station, a location of the user terminal within an area serviced by the ground station;

selecting a number of satellite communication signal repeaters to relay the communication between the user terminal and the ground station, the selected number being a function of at least the determined location of the user terminal and also stored information describing a communication signal propagation environment at the determined location of the user terminal, the selected number of satellite communication signal repeaters being a number that provides at least a minimum communications quality while using a minimum amount of system resources; and

repeating the step of selecting, if required, during a time that the communication is established so as to continue to provide at least the minimum communications quality while using a minimum amount of system resources.