Satellite telecommunications system using network coordinating gateways operative with a terrestrial communication system

• US 5,448,623 A
• Filed: 03/20/1995
• Issued: 09/05/1995
• 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): Kuntz, Curtis
• Assistant Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US08/407,799
• Time in Patent Office: 169 Days
• Field of Search: 379/59, 379/60, 455/12, 455/13.1
• 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.

Claims

1. A satellite communications system operative with at least one existing terrestrial communication system, comprising:

at least one satellite in earth orbit;

at least one terrestrial gateway that is bidirectionally coupled to said at least one existing terrestrial communications system, said at least one terrestrial gateway further being bidirectionally coupled through first RF links to said at least one satellite for transmitting communications traffic to, and for receiving communications traffic from, said at least one satellite;

a plurality of transceivers associated with users of said satellite communications system, each of said plurality of transceivers being bidirectionally coupled, when active, through second RF links to said at least one satellite for transmitting communications traffic to, and for receiving communications traffic from, said at least one satellite;

a terrestrial data network; and

at least one network coordinating gateway coupled to said at least one satellite through said first RF links for receiving requests for service from active transceivers, said at least one network coordinating gateway further being bidirectionally coupled through said terrestrial data network to said at least one terrestrial gateway for commanding said at least one terrestrial gateway to establish bidirectional communication links between selected ones of active transceivers that are requesting service and said existing terrestrial communications system;

wherein

communications traffic to an active one of said selected transceivers is passed through and repeated by said at least one satellite by being received from one of said first RF links, frequency shifted, and transmitted to one of said second RF links, without regard for any informational content of said communications traffic; and

wherein

communications traffic from an active one of said selected transceivers is passed through and repeated by said at least one satellite by being received from one of said second RF links, frequency shifted, and transmitted to one of said first RF links, without regard for any informational content of said communications traffic.

2. A satellite communication system as set forth in claim 1 wherein said first RF links use frequencies within a first band of RF frequencies, and wherein said second RF links use frequencies within a second band of RF frequencies that differs from said first band of RF frequencies.

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

4. A satellite communications system as set forth in claim 1 wherein said at least one satellite is one of a plurality of satellites forming a constellation of earth orbit satellites, and further comprising a handoff controller coupled to said at least one terrestrial gateway for handing off, from a first satellite to a second satellite, a bidirectional communication link that is established with an active user terminal.

5. A satellite communications system as set forth in claim 1 wherein said communications traffic is conveyed over said first RF links and said second RF links using a spread spectrum, code division multiple access technique.

6. A satellite communications system as set forth in claim 1, wherein a request for service from one of said plurality of transceivers is passed through and repeated by said at least one satellite without regard for any informational content of said request for service.

7. A satellite communications system operative with at least one existing terrestrial communication system, comprising:

at least one satellite in earth orbit;

a plurality of terrestrial gateways each of which is bidirectionally coupled to said at least one existing terrestrial communications system, said plurality of terrestrial gateways each further being bidirectionally coupled through first RF links to said at least one satellite for transmitting communications traffic to, and for receiving communications traffic from, said at least one satellite;

a plurality of transceivers associated with users of said satellite communications system, each of said plurality of transceivers being bidirectionally coupled, when active, through second RF links to said at least one satellite for transmitting communications traffic to, and for receiving communications traffic from, said at least one satellite;

a terrestrial controller maintaining a network database of user transceiver-related data;

a terrestrial data network for coupling together said plurality of terrestrial gateways and said terrestrial controller; and

at least one network coordinating gateway coupled to said at least one satellite through said first RF links for receiving requests for service from active transceivers, said at least one network coordinating gateway including means for determining a location of an active transceiver that is requesting service and for selecting, in accordance with said determined location, a terrestrial gateway to establish a bidirectional communication link between said active transceiver that is requesting service and said existing terrestrial communications system;

wherein

communications traffic to an active one of said selected transceivers is passed through and repeated by said at least one satellite by being received from one of said first RF links, frequency shifted and transmitted to one of said second RF links, without regard for any informational content of said communications traffic; and

wherein

communications traffic from an active one of said selected transceivers is passed through and repeated by said at least one satellite by being received from one of said second RF links, frequency shifted and transmitted to one of said first RF links, without regard for any informational content of said communications traffic.

8. A satellite communication system as set forth in claim 7 wherein said first RF links use frequencies within a first band of RF frequencies, and wherein said second RF links use frequencies within a second band of RF frequencies that differs from said first band of RF frequencies.

9. A satellite communication system as set forth in claim 7 and further comprising a satellite communications system database that is bidirectionally coupled to and maintained by said at least one network coordinating gateway, said satellite communications system database storing information for identifying at least (a) active transceivers, (b) a physical location of the active transceivers, and (c) a home terrestrial gateway of the active transceivers.

10. A satellite communications system as set forth in claim 7 wherein said at least one satellite is one of a plurality of satellites forming a constellation of earth orbit satellites, and further comprising a handoff controller coupled to said at least one terrestrial gateway for handing off from a first satellite to a second satellite a bidirectional communication link that is established with an active user terminal.

11. A satellite communications system as set forth in claim 7 wherein said communications traffic is conveyed over said first RF links and said second RF links using a spread spectrum, code division multiple access technique.

12. A satellite communications system as set forth in claim 7, wherein requests for service from transceivers is passed through and repeated by a satellite without regard for any informational content of said requests for service.

13. A satellite communications system as set forth in claim 7 wherein each of said plurality of terrestrial gateways is associated with a service coverage area and is comprised of:

a database recording information descriptive of home transceivers; and

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

wherein

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

14. A satellite communications system as set forth in claim 7 wherein each of said plurality of transceivers is capable of operation in accordance with at least one of simplex and full duplex.

15. 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 at least one satellite in earth orbit;

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 the at least one satellite 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 and further being bidirectionally coupled, through a terrestrial data network, to a plurality of terrestrial gateways each having an associated service area, individual ones of the plurality of terrestrial gateways being bidirectionally coupled to the terrestrial communications network and further being 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;

selecting, with the network coordinating gateway, one the plurality of terrestrial gateways to couple the wireless transceiver requesting service to the terrestrial communications network;

transmitting a command over the terrestrial data network from the network coordinating gateway to the selected one of the terrestrial gateways, the transmitted command instructing the selected one of the terrestrial gateways to establish a wireless communication link between the wireless transceiver requesting service and the terrestrial communications network; and

in response to the selected one of the terrestrial gateways establishing the wireless communications link between the wireless transceiver requesting service and the terrestrial communications network, the established wireless communications 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.

16. A method as set forth in claim 15 and further comprising a step of maintaining a satellite communications system database that is bidirectionally coupled to the least one network coordinating gateway, the satellite communications system database storing information 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.

17. A method as set forth in claim 15 wherein the at least one satellite is one of a plurality of satellites forming a constellation of earth orbit satellites, and further comprising a step of transferring the established wireless communications link from a first satellite to a second satellite.

18. A method as set forth in claim 15 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 spread spectrum, code division multiple access signals.

19. 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 at least one satellite in earth orbit;

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 the at least one satellite 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 and further being bidirectionally coupled, through a terrestrial data network, to a network controller and a plurality of terrestrial gateways, individual ones of the plurality of terrestrial gateways being bidirectionally coupled to the terrestrial communications network and further being 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;

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

selecting, with the network coordinating gateway, one 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; and

in response to the selected one of the terrestrial gateways establishing the wireless communications link between the wireless transceiver requesting service and the terrestrial communications network, the established wireless communications 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.

20. A method as set forth in claim 19 and further comprising a step of maintaining a satellite communications system database that is bidirectionally coupled to the least one network coordinating gateway, the satellite communications system database storing information 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.

21. A method as set forth in claim 19 wherein the at least one satellite is one of a plurality of satellites forming a constellation of earth orbit satellites, and further comprising a step of transferring the established wireless communications link from a first satellite to a second satellite.

22. A method as set forth in claim 19 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 spread spectrum, code division multiple access signals.

23. A method as set forth in claim 19 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.

24. A method as set forth in claim 19, and further comprising a step 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 the at least one satellite to the specified one of the plurality of wireless terminals.