Communication system utilizing multiple satellites without intersatellite crosslinks

• US 6,628,922 B1
• Filed: 03/21/2000
• Issued: 09/30/2003
• Est. Priority Date: 03/21/2000
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Berger, Harvey L., Jue, Reginald, Nivens, Dennis A.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): LELE, TANMAY S
• Application Number:
  US09/532,184
• Time in Patent Office: 1,288 Days
• Field of Search: 455/427, 455/428, 455/429, 455/430, 455/12.1, 455/13.1, 455/13.2, 455/13.3, 455/16, 455/447, 455/454, 455/446, 370/316, 370/321, 370/327
• US Class Current: 455/13.1
• CPC Class Codes: H04B 7/18584 Arrangements for data networking, i.e. for data packet routing, for congestion control data switching networks H04L12/00

Abstract

A communications system includes two satellites located at the same node along the geostationary arc each capable of receiving RF signals through an uplink channel and transmitting RF signals through a downlink channel distinct from the uplink channels. At least two user terminals are in the system, with each user terminal able to transmit RF signals to only one of the satellites, but at least one of the user terminals is able to receive RF signals from both of the satellites.

Claims

1. A communications system comprising:

a first satellite in geostationary earth orbit (GEO), including means for receiving RF signals through a first uplink channel and for transmitting RF signals through a first downlink channel distinct from said first uplink channel;

a second satellite in geostationary earth orbit (GEO), including means for receiving RF signals through a second uplink channel distinct from said first uplink channel, and for transmitting RF signals through a second downlink channel distinct from said first downlink channel and said second uplink channel;

a first user terminal in RF communication with said first satellite, said first user terminal transmitting RF signals to said first satellite through said first uplink channel and receiving RF signals from said first satellite through said first downlink channel, said first user terminal further including means for receiving RF signals from said second satellite through said second downlink channel; and

a second user terminal in RF communication with said first satellite, said second user terminal transmitting RF signals to said second satellite through said second uplink channel and receiving RF signals from said first satellite through said second downlink channel, said second user terminal further including means for receiving RF signals from said first satellite through said second downlink channel;

wherein the term distinct means non-interfering and different with respect to at least one of the properties of frequency and polarization of the RF signals.

2. The communications system according to claim 1 including a third user terminal in RF communication with said second satellite, said third user terminal transmitting RF signals to said second satellite through said second uplink channel and receiving RF signals from said second satellite through said second downlink channel, said third user terminal incapable of receiving RF signals from said first satellite through said first downlink channel.

3. The communications system according to claim 1 wherein said first uplink channel operates at a first frequency, said second uplink channel operates at a second frequency, said first downlink channel operates at a third frequency, and said second downlink channel operates at a fourth frequency.

4. The communications system according to claim 1 wherein said first uplink channel operates at a first polarization, said second uplink channel operates at a second polarization, said first downlink channel operates at a third polarization, and said second downlink channel operates at a fourth polarization.

5. The communications system according to claim 1 wherein said RF signals are time division multiple access signals.

6. A communications system comprising:

a first satellite in geosynchronous earth orbit (GEO), including means for receiving RF signals through a first uplink channel and for transmitting RF signals through a first downlink channel distinct from said first uplink channel;

a second satellite in geosynchronous earth orbit (GEO), including means for receiving RF signals through a second uplink channel district from said first uplink channel, and for transmitting RF signals through a second downlink channel distinct from said first downlink channel and said second uplink channel;

a first user terminal in RF communication with said first satellite, said first user terminal transmitting RF signals to said first satellite through said first uplink channel and receiving RF signals from said first satellite through said first downlink channel, said first user terminal further including means for receiving RF signals from said second satelite through said second downlink channel; and

a second user terminal in RF communication with said second satellite, said second user terminal transmitting RF signals to said second satellite through said second uplink channel and receiving RF signals from said second satellite through said second downlink channel, said second user terminal incapable of receiving RF signals from said first satellite through said first downlink channel;

wherein the term distinct means non-interfering and different with respect to at least one of the properties of frequency and polarization of the RF signals;

and wherein the system further comprises a gateway station in RF communication with said first satellite, and said second satellite, said gateway station including means for determining the receiving capability of said second user terminal, and means for routing RF signals received from said first satellite through said first downlink channel to said second user terminal through said second satellite.

7. The communication system according to claim 6 further including means located on the first satellite for receiving information concerning the receiving capability of said second user terminal and for transmitting the RF signals to said gateway station based on the capability of the second user terminal to receive RF signals from said first satellite.