Satellite communication system that is coupled to a terrestrial communication network and method

• US 5,594,780 A
• Filed: 06/02/1995
• Issued: 01/14/1997
• Est. Priority Date: 10/10/1991
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated
• Original Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Inventors: Wiedeman, Robert A., Monte, Paul A.
• Primary Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US08/459,105
• Time in Patent Office: 592 Days
• Field of Search: 370/104.1, 370/18, 379/59, 379/60, 244/158 R, 342/353, 342/354, 342/371, 342/373, 375/99, 375/102, 375/200, 455/10, 455/11.1, 455/12.1, 455/12.2, 455/13.1, 455/13.2, 455/33.1, 455/33.2, 455/33.4, 455/56.1, 455/65, 455/68, 455/52.3, 455/70, 455/303
• US Class Current: 455/430
• CPC Class Codes: H04B 7/18541 for handover of resources
• CPC Class Codes: H04B 7/18556 using a location database

Abstract

A wireless telephone system (10) capable of servicing a roaming wireless telephone user (30) includes a satellite (22) communications system consisting of at least one orbiting satellite (22); at least one terrestrial-based gateway (12, 14, 16, 18) having access to a database (20) of users, destination codes (telephone numbers); at least one network coordinating gateway (28) within at least one satellite service area (24); a single network control center (25); and a plurality of terrestrial communications links (e.g. 101). The system (10) operates by effecting communication between a terrestrial wireless telephone end user transceiver apparatus (e.g. 501) and a terrestrial communications link (e.g. 101) via a single relay through a single satellite (22) or a succession of single relay satellites (22) wherein the relay station may be in motion relative to the end user transceiver apparatus (501) and the terrestrial communications link (101). The ground-based gateway (28) effects the ultimate decision on linking in cooperation with the network database to effect hand-off from a first orbiting satellite (22) to a second orbiting satellite (22). The single satellite (22) or preferably a constellation of satellites (22) orbiting near the earth need only translate signals from the gateways (12, 14, 16, 18) to the users (30) and from the users (30) to the gateways (12, 14, 16, 18), without satellite-based control. The gateways (12, 14, 16, 18) are capable of decoding the calls, switching, processing call requests from the end users (30), processing call requests to the end users (30), processing call set-ups, handing off of calls to other satellites (22), and updating databases (20) of users (30) based on information provided by network control (25) and requests from end users (30).

Claims

1. A method for performing wireless communications in a satellite communications system that is bidirectionally coupled to a terrestrial communications network, comprising the steps of:

providing a plurality of earth orbiting satellites;

initiating a request for service with a wireless transceiver of a group of wireless transceivers associated with users of the satellite communications system, individual ones of the group of wireless transceivers being bidirectionally coupled, when active, through first RF links to at least one satellite of the plurality of earth orbiting satellites for transmitting communications signals to, and for receiving communications signals from, the at least one satellite;

transmitting the request for service from the wireless transceiver over one of the first RF links to the at least one satellite;

repeating the request for service by receiving the request for service with the at least one satellite from the one of the first RF links, frequency shifting the received request for service, and transmitting the frequency shifted request for service to one of second RF links, without regard for any informational content of the request for service;

receiving the repeated request for service with at least one network coordinating gateway, the at least one network coordinating gateway being bidirectionally coupled to the at least one satellite through the second RF links;

providing a plurality of terrestrial gateways that are bidirectionally coupled through the second RF links to the at least one satellite for transmitting communications signals to, and for receiving communications signals from, the at least one satellite, each of the plurality of terrestrial gateways also being bidirectionally coupled to a terrestrial communications network;

determining, with the network coordinating gateway, a location of the wireless transceiver that is requesting service;

selecting, with the network coordinating gateway, one of the plurality of terrestrial gateways to couple the wireless transceiver requesting service to the terrestrial communications network, the terrestrial gateway being selected in accordance with at least the determined location of the wireless transceiver that is requesting service;

establishing a wireless communication link between the wireless transceiver requesting service and the terrestrial communications network through the selected one of the terrestrial gateways; and

in response to the selected one of the terrestrial gateways establishing the wireless communication link between the wireless transceiver requesting service and the terrestrial communications network, the established wireless communication link having a first uplink communications signal component from the wireless transceiver to the at least one satellite, a first downlink communications signal component from the at least one satellite to the selected terrestrial gateway, a second uplink communications signal component from the terrestrial gateway to the at least one satellite, and a second downlink communications signal component from the at least one satellite to the wireless transceiver,

repeating the first uplink communications signals with the at least one satellite by receiving the first uplink communications signals, frequency shifting the received first uplink communications signals, and transmitting the frequency shifted first uplink communications signals as the first downlink communications signals, without regard for any informational content of the first uplink communications signals; and

repeating the second uplink communications signals with the at least one satellite by receiving the second uplink communications signals, frequency shifting the received second uplink communications signals, and transmitting the frequency shifted second uplink communications signals as the second downlink communications signals, without regard for any informational content of the second uplink communications signals;

wherein

the step of repeating the request for service, the step of repeating the first uplink communications signals, and the step of repeating the second uplink communications signals all repeat code division multiple access signals; and

wherein

the step of establishing the wireless communication link includes a step of transmitting at least one code to the wireless transceiver requesting service, the at least one code being used for at least one of (a) modulating a communication signal that is transmitted from the wireless transceiver using the first uplink communications signal component, and (b) demodulating a communication signal that is transmitted to the wireless transceiver using the second downlink communications signal component.

2. A method as set forth in claim 1, and further comprising a step of maintaining a satellite communications system database that is bidirectionally coupled to the least one network coordinating gateway, the step of maintaining including a step of storing information in the satellite communications system database for identifying at least (a) active wireless transceivers, (b) a physical location of the active wireless transceivers, and (c) a home terrestrial gateway of the active wireless transceivers.

3. A method as set forth in claim 1, and further comprising a step of transferring the established wireless communication link from a first .satellite to a second satellite.

4. A method as set forth in claim 1 wherein each of the plurality of terrestrial gateways is associated with a service coverage area, and further comprising the terrestrial gateway executed steps of:

maintaining a database that records information descriptive of home wireless transceivers; and

maintaining a database that records information descriptive of active wireless transceivers that are located within the service coverage area that is associated with the terrestrial gateway;

wherein

the selected terrestrial gateway is responsive to a condition that an identification of a wireless transceiver requesting service is not found in the database of home transceivers, for updating the database of active wireless transceivers to include an identification of the wireless transceiver requesting service.

5. A method as set forth in claim 1, and further comprising the steps of:

initiating, with a transceiver that is coupled to the terrestrial communications network, a request to establish a communications link with a specified one of the plurality of wireless transceivers;

routing the request through the terrestrial communications network to a home user database to determine a current location of the specified one of the plurality of wireless transceivers;

further routing the request through the terrestrial communications network to a terrestrial gateway having a service coverage area that includes the location of the specified one of the plurality of wireless transceivers;

determining in the terrestrial gateway if satellite and terrestrial gateway resources are available to establish the communications link; and

if it is determined that the resources are available, establishing the communications link from the transceiver coupled to the terrestrial communications network, through the terrestrial gateway, and through at least one satellite to the specified one of the plurality of wireless terminals.

6. A satellite communications system that is bidirectionally coupled to a terrestrial communications network, comprising:

a plurality of earth orbiting satellites;

at least one wireless transceiver associated with a user of the satellite communications system, said wireless transceiver comprising first means for bidirectionally coupling said wireless transceiver, when active, through first RF links to at least one satellite of the plurality of earth orbiting satellites for transmitting communications signals to, and for receiving communications signals from, the at least one satellite, said first means for bidirectionally coupling being response to input from the user for transmitting a request for service from the wireless transceiver over one of the first RF links to the at least one satellite, said wireless transceiver further comprising second means for bidirectionally coupling said wireless transceiver, when active, through other RF links to a terrestrial cellular communications system for transmitting communications signals to, and for receiving communications signals from, the terrestrial cellular communications system;

said at least one satellite comprising means for repeating the request for service by receiving the request for service from the one of the first RF links, for frequency shifting the received request for service, and for transmitting the frequency shifted request for service to one of second RF links, without regard for any informational content of the request for service;

a plurality of terrestrial gateways that are bidirectionally coupled through the second RF links to the at least one satellite for transmitting communications signals to, and for receiving communications signals from, the at least one satellite, each of the plurality of terrestrial gateways also being bidirectionally coupled to a terrestrial communications network; and

a network coordinating gateway comprising means for receiving the request for service from the one of the second RF links, said network coordinating gateway further comprising means for determining a location of the wireless transceiver that is requesting service and for selecting one of the plurality of terrestrial gateways to couple the wireless transceiver requesting service to the terrestrial communications network, the terrestrial gateway being selected in accordance with at least the determined location of the wireless transceiver that is requesting service;

wherein

each of said terrestrial gateways further comprises means for establishing a wireless communication link between the wireless transceiver requesting service and the terrestrial communications network, the established wireless communication link having a first uplink communications signal component from the wireless transceiver to the at least one satellite, a first downlink communications signal component from the at least one satellite to the selected terrestrial gateway, a second uplink communications signal component from the terrestrial gateway to the at least one satellite, and a second downlink communications signal component from the at least one satellite to the wireless transceiver; and

wherein

said repeating means of said at least one satellite repeats the first uplink communications signals by receiving the first uplink communications signals, frequency shifting the received first uplink communications signals, and transmitting the frequency shifted first uplink communications signals as the first downlink communications signals, without regard for any informational content of the first uplink communications signals, and also repeats the second uplink communications signals by receiving the second uplink communications signals, frequency shifting the received second uplink communications signals, and transmitting the frequency shifted second uplink communications signals as the second downlink communications signals, without regard for any informational content of the second uplink communications signals.

7. A satellite communications system as set forth in claim 6, wherein individual ones of said terrestrial gateways are bidirectionally coupled to said terrestrial communications network though a cellular telephone interface unit.

8. A satellite communications system as set forth in claim 6, wherein individual ones of said terrestrial gateways further comprise a handoff processor for handing off an established wireless communications link from a first satellite to a second satellite.

9. A satellite communications system as set forth in claim 6, wherein said network coordinating gateway is bidirectionally coupled to said terrestrial communications network though a cellular telephone interface unit.

10. A satellite communications system as set forth in claim 6, wherein said network coordinating gateway is colocated with one of said plurality of terrestrial gateways.

11. A satellite communications system as set forth in claim 6, wherein said network coordinating gateway is coupled to said terrestrial gateways for receiving at least terrestrial gateway status signals and user roaming requests from said terrestrial gateways.

12. A satellite communications system as set forth in claim 6, wherein said network coordinating gateway is coupled to said terrestrial gateways for transmitting at least call setup information to said terrestrial gateways.

13. A satellite communications system as set forth in claim 6, wherein said plurality of satellites are a constellation of low earth orbit satellites.

14. A satellite communications system that is bidirectionally coupled to a terrestrial communications network, comprising:

a plurality of earth orbiting satellites;

a plurality of wireless transceivers associated with users of the satellite communications system, each of said wireless transceivers comprising first means for bidirectionally coupling said wireless transceiver, when active, through a first RF link to at least one satellite of the plurality of earth orbiting satellites for transmitting communications signals to, and for receiving communications signals from, the at least one satellite, said first means for bidirectionally coupling being response to input from the user for transmitting a request for service from the wireless transceiver over said first RF link to the at least one satellite;

said at least one satellite comprising means for repeating the request for service by receiving the request for service from the one of the first RF links, for frequency shifting the received request for service, and for transmitting the frequency shifted request for service to a second RF link, without regard for any informational content of the request for service; and

a plurality of gateways that are bidirectionally coupled through the second RF link to the at least one satellite for transmitting communications signals to, and for receiving communications signals from, the at least one satellite, each of the plurality of gateways also being bidirectionally coupled to a terrestrial communications network, at least one of said gateways functioning as a network coordinating gateway and comprising means for receiving requests for service from the second RF link, said network coordinating gateway further comprising means for determining a location of the wireless transceiver that is requesting service and for selecting one of the plurality of gateways to couple the wireless transceiver requesting service to the terrestrial communications network, the gateway being selected in accordance with at least the determined location of the wireless transceiver that is requesting service.

15. A satellite communications system as set forth in claim 14, wherein each of said gateways further comprises means for establishing a wireless communication link between the wireless transceiver requesting service and the terrestrial communications network, the established wireless communication link having a first uplink communications signal component from the wireless transceiver to the at least one satellite, a first downlink communications signal component from the at least one satellite to the selected gateway, a second uplink communications signal component from the selected gateway to the at least one satellite, and a second downlink communications signal component from the at least one satellite to the wireless transceiver;

and wherein said repeating means of said at least one satellite repeats the first uplink communications signals by receiving the first uplink communications signals, frequency shifting the received first uplink communications signals, and transmitting the frequency shifted first uplink communications signals as the first downlink communications signals, without regard for any informational content of the first uplink communications signals, and also repeats the second uplink communications signals by receiving the second uplink communications signals, frequency shifting the received second uplink communications signals, and transmitting the frequency shifted second uplink communications signals as the second downlink communications signals, without regard for any informational content of the second uplink communications signals.

16. A satellite communications system as set forth in claim 14, wherein said plurality of wireless transceivers further comprise second means for bidirectionally coupling said wireless transceiver, when active, through other RF links to a terrestrial cellular communications system for transmitting communications signals to, and for receiving communications signals from, the terrestrial cellular communications system.

17. A satellite communications system as set forth in claim 14, wherein individual ones of said gateways are bidirectionally coupled to said terrestrial communications network though a cellular telephone interface unit.

18. A satellite communications system as set forth in claim 14, wherein individual ones of said gateways further comprise a handoff processor for handing off an established wireless communications link from a first satellite to a second satellite.

19. A satellite communications system as set forth in claim 14, wherein said network coordinating gateway is bidirectionally coupled to said terrestrial communications network though a cellular telephone interface unit.

20. A satellite communications system as set forth in claim 14, wherein said network coordinating gateway is bidirectionally coupled to said gateways for receiving at least terrestrial gateway status signals and user roaming requests from said gateways, and for transmitting at least call setup information to said gateways.