Architecture for an integrated mobile and fixed telecommunications system including a spacecraft

• US 5,907,541 A
• Filed: 10/20/1997
• Issued: 05/25/1999
• Est. Priority Date: 09/17/1997
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Whitaker, Dennis Clifton, Fairholm, Daniel Wayne
• Primary Examiner(s): Vu, Huy D.
• Assistant Examiner(s): BOAKYE, ALEXANDER O
• Application Number:
  US08/957,753
• Time in Patent Office: 582 Days
• Field of Search: 370/321, 370/322, 370/323, 370/325, 370/330, 370/436, 370/478, 455/427, 455/428, 455/429, 455/430, 455/450, 455/454, 455/553
• US Class Current: 370/316
• CPC Class Codes: H04B 7/18563 Arrangements for interconnecting multiple systems data switching networks H04L12/00
• CPC Class Codes: H04W 84/14 WLL [Wireless Local Loop]; RLL [Radio Local Loop]

Abstract

A communication system (10) includes a plurality of fixed terrestrial gateway terminals (14) and fixed village terminals (18), and also includes a plurality of mobile user terminals (16). The system includes a first satellite (12m) which provides communication in a bent-pipe manner between user terminals (16) lying in spot-beams of the first satellite'"'"'s antenna and gateway terminals (18) lying in a broad antenna beam. The system also includes a second satellite which provides communications in a bent-pipe manner between or among the gateways/village terminals. The village terminals differ from the gateways in that the village terminals do not include the subscriber of user home or visitor registers. The village terminal includes a wireless local communication system such as a WLL, for communicating with user terminals (16) lying within its range. The user terminals (16) are dual-mode. In a first operating mode, the user terminals (16) communicate with other users by way of the village terminal when within its range, and otherwise switch to a second mode, in which they communicate by way of the first satellite. The village terminal communicates with gateways by means of the second spacecraft.

Claims

1. A spacecraft-based cellular frequency- and time-division multiple access communication system for communication among terrestrial user terminals, terrestrial gateway terminals, and terrestrial village terminals, said communication system comprising:

a satellite-based first transceiver arrangement, said first transceiver arrangement including a first frequency-dependent routing arrangement, a first transmitting arrangement, a first receiving arrangement, and an antenna arrangement coupled to said transmitting and receiving arrangements, which antenna arrangement includes a first antenna which forms a plurality of spot beams directed toward the Earth'"'"'s surface, each in a different direction, so that each beam overlies a different terrestrial footprint, and a second antenna which produces at least one broad beam directed toward the Earth'"'"'s surface, said first transceiver arrangement being at least for (a) receiving, over said broad beam, forward traffic signals transmitted within a first uplink frequency band from at least one of said gateway terminals, and for frequency shifting said forward traffic signals to a first downlink frequency band, and for retransmitting said forward traffic signals in said first downlink frequency band over at least one of said spot beams to at least some of said user terminals lying within said footprint of said one of said spot beams, and (b) for receiving, over at least one of said spot beams, return traffic signals transmitted within a second uplink frequency band from at least one of said user terminals lying in the footprint associated with that one of said spot beams, and for frequency shifting said return traffic signals to a second downlink frequency band, and for retransmitting said return traffic signals in said second downlink frequency band over said broad beam to at least some of said gateway terminals lying within said footprint of said broad beam, whereby said first transceiver operates in a bent-pipe manner to provide communications between said user terminals on the one hand and said gateway terminals on the other hand;

a satellite-based second transceiver arrangement, said second transceiver arrangement operating in a bent-pipe manner for providing communications among said village and gateway terminals, and not with said user terminals;

at least one terrestrial gateway terminal including subscriber home and visitor registers, for storing information about communication system subscribers, each of said gateway terminals being coupled to at least one public network, which public network may be one of a public switched telephone network and a public land mobile network, for providing communication, by way of said second transceiver arrangement, between said public network and others of said gateway terminals and said village terminals, and by way of said first transceiver arrangement, between said public network and said user terminals;

at least one terrestrial village terminal, said village terminal providing communication by way of said second transceiver arrangement with at least one of said gateway terminals, said village terminal differing from said gateway terminals in that said village terminal lacks said subscriber home location register and said subscriber visitor location register, and said village terminal further differing from said gateway terminals in that each said village terminal includes at least one cell of a wireless land-based cellular communication system having a limited effective range, said cell of said village terminal being for providing communications among those of said user terminals within said effective range of said cell of said village terminal, and, by way of said second transceiver arrangement, between at least one of said gateway terminals and those of said user terminals within said effective range of said cell of said village terminal; and

at least one terrestrial dual-operating-mode user terminal, for, when said dual-operating-mode user terminal is within said effective range of said cell of said village terminal, operating in a first mode by which communications are made between said dual-operating-mode subscriber terminal and said village terminal, and, when said dual-operating-mode terminal is not within range of any village terminal, operating in a second mode by which said dual-operating-mode user terminal communicate with said first transponder arrangement, whereby, in said first mode, said dual-operating-mode user terminal may communicates with others of said user terminals within said range of said village terminal by way of said village terminal, and in said second mode, said dual-operating-mode user terminal communicates with others of said user terminals by way of at least said first transceiver, and whereby, in said first mode, said dual-operating-mode user terminal communicates with said gateway terminals by way of said village terminal and said second transceiver, and in said second mode of operation, said dual-operating-mode user terminal communicates with one of said gateway terminals by way of said first transceiver.

2. A system according to claim 1, wherein said first and second transceivers are located on first and second satellites, respectively.

3. A system according to claim 2, wherein said first and second satellites are in geosynchronous orbits.