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 Title: |
US5408237:
Earth-fixed cell beam management for satellite communication system
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Patterson, David P.; Los Altos, CA
Sturza, Mark A.; Woodland Hills, CA
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| Assignee: |
Teledesic Corporation, Kirkland, WA
other patents from TELEDESIC CORPORATION (710519) (approx. 10)
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| Published / Filed: |
1995-04-18
/ 1993-07-08
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| Application Number: |
US1993000088714
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| IPC Code: |
Advanced:
H01Q 1/28;
H01Q 3/24;
H01Q 15/02;
H01Q 25/00;
H04B 7/15;
H04B 7/204;
H04B 7/26;
H04Q 7/34;
H04Q 7/36;
H04B 7/185;
Core:
H01Q 1/27;
H01Q 15/00;
more...
IPC-7:
G01S 5/02;
H04B 7/185;
H04M 11/00;
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| ECLA Code: |
H01Q1/28F; H01Q3/24; H01Q15/02; H01Q25/00D7B; H04B7/204B;
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| U.S. Class: |
Current:
342/354;
342/357.16;
455/012.1;
455/013.1;
455/013.2;
455/013.3;
455/428;
455/429;
Original:
342/354;
342/357;
455/012.1;
455/013.3;
379/058;
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| Field of Search: |
342/354,357,368
455/12.1,13.3
379/058
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| Priority Number: |
| 1993-07-08 |
US1993000088714 |
| 1991-11-08 |
US1991000790318 |
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| Abstract: |
Earth-fixed cell beam management methods which may be employed to allocate beams generated by a constellation of low Earth orbit satellites (12) flying in orbits below geosynchronous altitudes are disclosed. These beams (19) are electronically steered so that they illuminate "Earth-fixed cells" (26) as opposed to "satellite-fixed cells." In a system that employs satellite-fixed cells, the "footprint" of the beams propagated by a spacecraft defines the zone on the ground called a "cell" which is illuminated by the spacecraft. This satellite-fixed cell moves constantly as the spacecraft moves around the globe. In sharp contrast, an "Earth-fixed cell" (26) is a stationary region mapped onto the surface of the Earth (E) that has permanent fixed boundaries, just like a city or a state. Although the rapidly moving satellites (12) still shine their beams over the ground in rapidly moving footprints (16), the locations of the footprints at any given time do not determine the location of the unchanging Earth-fixed cells (26). The great advantage provided by using cells having boundaries that are fixed to an Earth-fixed grid (20) is realized when a subscriber being served by one satellite must switch to another beam in the same satellite or to a second satellite because the first is moving out of range below the local horizon. With satellite-fixed cells, this "hand-off" involves the assignment to the terminal of a new communication channel within the new beam or new satellite. This assignment process takes time and consumes processing capacity at both the terminal and the satellite. It is also subject to blocking, call interruption, and call dropping if there is not an idle communication channel in the next serving beam or satellite. The Earth-fixed cell method avoids these problems by allocating communication channels (frequency, code, and/or time slot) on an Earth-fixed cell basis rather than on a satellite-fixed cell basis. Regardless of which satellite/beam is currently serving a particular cell, the terminal maintains the same channel assignment, thus ameliorating the "hand-off" problem.
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| Attorney, Agent or Firm: |
Anglin & Giaccherini ;
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| Primary / Asst. Examiners: |
Issing, Gregory C.;
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| Maintenance Status: |
CC Certificate of Correction issued
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| INPADOC Legal Status: |
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Family Legal Status Report
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| Parent Case: |
CROSS-REFERENCES TO RELATED PATENT APPLICATIONS
The present patent application is related to the following commonly-owned and commonly-assigned patent applications:
Satellite Communication System by Edward F. Tuck et al., filed on Oct. 28, 1991 and assigned U.S. Ser. No. 07/783,754;
Terrestrial Antennas for Satellite Communication System by Asu Ram Jha, a Continuation-in-Part application filed on Dec. 2, 1992 and assigned U.S. Ser. No. 07/984,609 and claiming the benefit of priority of a parent application entitled Terrestrial Antennas for Satellite Communication System by Asu Ram Jha, filed Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,273;
Switching Methods for Satellite Communication System by David Palmer Patterson & Moshe Lerner Liron, filed on Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,805;
Spacecraft Antennas & Beam Steering Methods for Satellite Communication System by Douglas Gene Lockie, filed on Oct. 28, 1992 and assigned U.S. Ser. No. 07/967,988 and claiming the benefit of priority of a parent application entitled Spacecraft Antennas & Beam Steering Methods for Satellite Communication System by Douglas Gene Lockie, filed on Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,271;
Spacecraft Designs for Satellite Communication System by James R. Smart and David P. Patterson, filed on Aug. 18, 1992 and assigned U.S. Ser. No. 07/931,625 and claiming the benefit of priority of a parent application entitled Spacecraft Designs for Satellite Communication System by James R. Smart filed on Nov. 8, 1991 and assigned U.S. Ser. No. 07/790,748;
Spacecraft Intersatellite Link for Satellite Communication System by Douglas G. Lockie et al., filed on Jul. 16, 1992 and assigned U.S. Ser. No. 07/915,172;
Method of Conducting a Telecommunications Business Implemented on a Computer by Edward F. Tuck, filed on Jun. 8, 1992 and assigned U.S. Ser. No. 07/895,295;
Traffic Routing for Satellite Communication System by Moshe Lerner Liron, filed on Feb. 9, 1993 and assigned U.S. Ser. No. 08/016,204; and
Modular Communication Satellite by James R. Smart, filed on Jun. 11, 1993 and assigned U.S. Ser. No. 08/075,425.
CLAIM FOR PRIORITY
The present application is a Continuation in Part application. The inventors hereby claim the benefit of priority under Section 120 of Title 35 of the United States Code of Laws for any and all subject matter which is commonly disclosed in the present application and in pending patent application U.S. Ser. No. 07/790,318, now abandoned, entitled Beam Compensation Methods for Satellite Communication System by David P. Patterson et al., filed on Nov. 8, 1991.
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| Designated Country: |
BB BG BR CA CS FI HU KP KR LK LU MG MN MW NO OA PL RO RU SD UA BE CH DK ES FR GB GR IE IT LI NL SE
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| Family: |
Show 22 known family members
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First Claim:
Show all 2 claims |
What is claimed is:
1. A method for allocating a plurality of beams (19) transmitted from and received at positions in Earth orbit for communicating with a plurality of portable (P), mobile (M) and fixed (F) terminals and gateways (G) comprising the steps of:
- forming a plurality of footprints (16) using a plurality of electronically steered, antenna elements (13a, 13b and 13c) which generate said plurality of beams (19);
- said plurality of antenna elements (13a, 13b and 13c) being carried onboard a plurality of satellites (12) flying in orbits (11) below geosynchronous altitude;
- one of said plurality of satellites (12) including a first serving satellite (12a) and a second satellite (12b) positioned next to said first serving satellite (12a);
- said plurality of footprints (16) illuminating portions of an Earth-fixed grid (20) with said plurality of beams (19);
- said plurality of beams (19) being capable of conveying a plurality of packets (Pk);
- said Earth-fixed grid (20) defining a plurality of Earth-fixed supercells (24);
- said plurality of Earth-fixed supercells (24) including a plurality of Earth-fixed cells (26);
- said plurality of Earth-fixed cells (26) including a target Earth-fixed cell (26t);
- tracking a target Earth-fixed cell (26t) by using a sequence of individual antenna elements (13a, 13b, 13c) aboard said first serving satellite (12a) so that said plurality of beams (19) are maintained over said target Earth-fixed cell (26t) as long as one of said plurality of individual antenna elements (13a, 13b, 13c) aboard said first serving satellite (12a) is capable of serving said target Earth-fixed cell (26t);
- measuring the distance from said first serving satellite (12a) which is currently serving said target Earth-fixed cell (26t) to the centroid of said target Earth-fixed cell (26t);
- measuring the distance from said second satellite (12b) which is the next closest satellite to said target Earth-fixed cell (26t) compared to said first serving satellite (12a) to the centroid of said target Earth-fixed cell (26t); and
- switching responsibility for providing said plurality of beams (19) to said target Earth-fixed cell (26t)
- from said first serving satellite (12a) to said second next satellite (12b)
- when the distance from said second next satellite (12b) to the centroid of said target Earth-fixed cell (26t) is less than
- the distance from said first serving satellite (12a) to the centroid of said target Earth-fixed cell (26t).
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 114 U.S. patent(s) that reference this one
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| Foreign References: |
None
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| Other Abstract Info: |
DERABS G1995-161237
DERABS G1995-161237
DERABS G1998-239397
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| Other References: |
"Advanced Communications Technology Satellite (ACTS) . . . " L. Wright et al., Proceedings of the IEEE, vol. 78, No. 7, Jul. 1990, pp. 1165-1175.
(11 pages)
"A Multibeam Active Antenna for an European Contiguous Coverage at Ku-band," G. Bartolucci et al., Globecom 1989, vol. 3, pp. 1115-1119.
"A Metropolitan Area Radio System Using Scanning Pencil Beams," A. Acampora et al., IEEE Transactions on Communiciations, Jan. 1991, pp. 141-151.
(11 pages)
Cited by 3 patents
[ISI abstract]
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