Methods and apparatus for broadcasting regional information over a satellite communication system

• US 6,594,469 B1
• Filed: 08/29/2000
• Issued: 07/15/2003
• Est. Priority Date: 08/29/2000
• Status: Active Grant

• Current Assignee: Globalstar Incorporated
• Original Assignee: Globalstar Incorporated
• Inventors: Gallagher, Vijaya, Serri, John, Sites, Michael J.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Ferguson, Keith
• Application Number:
  US09/650,513
• Time in Patent Office: 1,050 Days
• Field of Search: 455/12.1, 455/13.3, 455/427, 455/428, 455/429, 455/430, 455/3.01, 455/3.02, 455/422, 455/550, 455/500, 455/403, 375/141, 370/316, 370/320, 370/315, 370/335, 370/342, 370/441, 342/352, 342/354
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18523 Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]

Abstract

In a communication satellite constellation which uses CDMA and multiple spot beams for point-to-point communication, a system is provided for broadcasting regionally related information within a spot beam by establishing a Frequency/Walsh Code Tiling over the Earth'"'"'s surface, and enabling a user terminal at a given position to tune to an appropriate frequency and Walsh Code to receive the information broadcast from a satellite over a forward beam downlink. The information, e.g. regional messages such as local weather or traffic, is transmitted to the satellite from a ground station or gateway that receives the information from a Broadcast Processing Center. In a preferred embodiment a dedicated Frequency Division Multiplex (FDM) channel within each spot beam transmits the regional broadcast messages at the Tiles in accordance with the Walsh Code designations of the Tiles.

Claims

1. A broadcast communication system, comprising:

at least one satellite;

at least one ground station for transmitting an uplink communication signal to said at least one satellite;

at least one broadcast information source having an output coupled to said at least one ground station for providing information to be broadcast thereto; and

a controller for assigning and unassigning codes to beams for handing over a particular broadcast region from one beam to another beam,

wherein said at least one satellite transmits a downlink communication signal comprised of a plurality of beams each having a beam coverage area on the ground, individual ones of said beams being capable of simultaneously conveying at least one broadcast communication and at least one point-to-point communication; and

wherein the ground is partitioned into a plurality of broadcast regions each of which is assigned an associated predetermined frequency and code that are a subset of a larger set of frequencies and codes used for point-to-point communications within the beam coverage areas.

2. A broadcast communication system as in claim 1, and further comprising at least one user terminal comprising a single receiver for receiving one of a broadcast communication or a point-to-point communication, said user terminal further comprising a memory for storing data descriptive of the assigned predetermined frequency and code for individual ones of said broadcast regions.

3. A broadcast communication system as in claim 1, and further comprising means for determining a current location of the user terminal, and a controller in said user terminal for associating the current location with a frequency and code that are assigned to the broadcast region that contains the current location of the user terminal.

4. A broadcast communication system as in claim 1, wherein said codes are comprised of Walsh Codes.

5. A broadcast communication system as in claim 1, wherein a particular frequency contains a plurality of said codes.

6. A broadcast satellite based telecommunication system, comprising:

a plurality of user terminals;

a constellation of non-geosynchronous satellites individual ones of which exhibit motion with respect to a point on the ground;

at least one ground station for transmitting an uplink communication signal to satellites in view of said ground station; and

at least one broadcast information source having an output coupled to said at least one ground station for providing broadcast content information thereto;

wherein individual ones of said satellites transmit a downlink user terminal communication signal comprised of a plurality of beams each having a beam coverage area on the ground, individual ones of said beams being capable of simultaneously conveying at least one broadcast communication to one user terminal in a first frequency channel and at least one point-to-point communication with another user terminal in one of a plurality of second frequency channels;

wherein within a particular geographical area the ground is partitioned into a plurality of broadcast regions which are collectively assigned to said first frequency channel, wherein individual ones of said broadcast regions are individually assigned to an individual one of a plurality of pseudo-noise codes; and

further comprising a gateway controller for performing beam-to-beam handovers of said broadcast regions due to motion of said beams over the ground.

7. A system as in claim 6, wherein said user terminal comprises a single receiver for receiving one of a broadcast communication or a point-to-point communication, said user terminal further comprising a memory for storing data descriptive of at least a mapping of pseudo-noise codes to said individual ones of said broadcast regions.

8. A system as in claim 7, and further comprising means for determining a current location of the user terminal, and a controller in said user terminal, responsive to said stored data, for determining at least a pseudo-noise code that is assigned to the broadcast region that contains the determined location of the user terminal.

9. A system as in claim 6, wherein said codes are comprised of Walsh Codes.

10. A system as in claim 6, wherein a particular frequency channel has a plurality of pseudo-noise codes.

11. A method for operating a satellite-based telecommunications system, comprising steps of:

tiling at least a portion of the surface of the Earth with a static Frequency/Walsh Code tiling;

storing information descriptive of the tiling;

operating a satellite user terminal so as to determine its current location;

associating the current location of the user terminal with a Frequency/Walsh Code, based on the stored information; and

further operating the satellite user terminal to acquire, using the Frequency/Walsh Code, a desired broadcast communication signal that is transmitted in a first satellite forward downlink beam.

12. A method as in claim 11, wherein the satellite forward link beam moves relative to a point on the ground, and further comprising a step of handing off at least the Walsh Code from the first satellite forward downlink beam to a second satellite forward downlink beam due to motion of the first satellite forward downlink beam away from the current location of the user terminal.