 |
|
|
|
|
|
 Title: |
US5736959:
Earth-fixed cell beam management for satellite communication system using dielectic lens-focused scanning beam antennas
[ Derwent Title ]
|
| Country: |
US United States of America
|
| |
| Inventor: |
Patterson, David Palmer; Bellevue, WA
Sturza, Mark Alan; Woodland Hills, CA
|
| Assignee: |
Teledesic Corporation, Kirkland, WA
other patents from TELEDESIC CORPORATION (710519) (approx. 10)
News, Profiles, Stocks and More about this company
|
| Published / Filed: |
1998-04-07
/ 1995-04-17
|
| Application Number: |
US1995000423677
|
| IPC Code: |
Advanced:
H01Q 1/24;
H01Q 1/28;
H01Q 3/24;
H01Q 3/26;
H01Q 5/00;
H01Q 15/02;
H01Q 21/06;
H01Q 25/00;
H04B 7/185;
H04B 7/195;
H04B 7/204;
Core:
H01Q 1/27;
H01Q 15/00;
more...
IPC-7:
H01Q 3/22;
H04B 7/185;
H04M 9/00;
|
| ECLA Code: |
H01Q1/24A1; H01Q1/24A1A1; H01Q1/28F; H01Q3/24; H01Q3/24B; H01Q3/26C; H01Q5/00C; H01Q15/02; H01Q21/06B3; H01Q25/00D7B; H04B7/185S8; H04B7/185S12; H04B7/195; H04B7/204B;
|
| U.S. Class: |
Current:
342/354;
342/372;
455/013.3;
Original:
342/354;
342/372;
379/060;
455/013.3;
|
| Field of Search: |
342/354,372
455/12.1,13.1,13.3
379/060
|
| Priority Number: |
| 1995-04-17 |
US1995000423677 |
| 1993-07-08 |
US1993000088714 |
| 1994-02-28 |
US1994000203140 |
| 1994-08-17 |
US1994000292148 |
| 1991-11-08 |
US1991000790318 |
| 1991-10-28 |
US1991000783754 |
|
| 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." Beam steering apparatus using a spherical dielectric lens (106) is disclosed. 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.
|
| Attorney, Agent or Firm: |
Christensen O'Connor Johnson & Kindness PLLC ;
|
| Primary / Asst. Examiners: |
Issing, Gregory C.;
|
| INPADOC Legal Status: |
Show legal status actions
Family Legal Status Report
|
|
|
|
|
|
|
| Parent Case: |
CLAIMS FOR PRIORITY
This application is a continuation-in-part of U.S. application Ser. No. 08/088,714, filed on Jul. 8, 1993 titled EARTH-FIXED CELL BEAM MANAGEMENT FOR SATELLITE COMMUNICATION SYSTEM, now U.S. Pat. No. 5,408,237, which was a continuation-in-part of application Ser. No. 07/790,318, filed on Nov. 8, 1991, titled BEAM COMPENSATION METHODS FOR SATELLITE COMMUNICATION SYSTEM, now abandoned. This application also is a continuation-in-part of application Ser. No. 08/203,140, filed on Feb. 28, 1994, titled SATELLITE COMMUNICATION SYSTEM, now abandoned, which was a continuation-in-part of application Ser. No. 07/783,754, filed on Oct. 28, 1991, titled SATELLITE COMMUNICATION SYSTEM, now abandoned. This application also is a continuation-in-part of application Ser. No. 08/292,148, filed on Aug. 17, 1994, titled DIELECTRIC LENS FOCUSED SCANNING BEAM ANTENNA FOR SATELLITE COMMUNICATION SYSTEM, now U.S. Pat. No. 5,548,294, which was a continuation-in-part of application Ser. No. 08/088,714 (referred to above and, in turn, a continuation-in-part of application Ser. No. 07/790,318, referred to above). Priority of the filing dates of these applications is claimed under 35 U.S.C. § 120.
|
| 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 GR IE LI NL SE FR GB IT
|
| Family: |
Show 24 known family members
|
First Claim:
Show all 11 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, 13c & 140) which generate said plurality of beams (19);
- said plurality of antenna elements (13a, 13b, 13c & 140) 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);
- scanning electronically, by using a sequence of individual antenna elements (13a, 13b, 13c & 140), each beam (19) of said plurality of beams (19) to the centroid of an Earth-fixed cell (26), which said Earth-fixed cell (26) is nearest to a nominal non-scanned position of said beam (19);
- addressing each said Earth-fixed cell (26) of said plurality of Earth-fixed cells (26) by shaping and focusing said beam (19) to illuminate said Earth-fixed cell (26), said illuminated Earth-fixed cell (26) being said target Earth-fixed cell (26t);
- tracking a target Earth-fixed cell (26t) by using said sequence of individual antenna elements (13a, 13b, 13c & 140) 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 & 140) 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 (1 2a) 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).
|
| Background / Summary: |
Show background / summary
|
| Drawing Descriptions: |
Show drawing descriptions
|
| Description: |
Show description
|
| Forward References: |
Show 64 U.S. patent(s) that reference this one
|
|
