Multiple satellite repeater capacity loading with multiple spread spectrum gateway antennas

• US 5,812,538 A
• Filed: 01/03/1997
• Issued: 09/22/1998
• Est. Priority Date: 06/06/1995
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated, Qualcomm, Inc.
• Original Assignee: Globalstar Incorporated, Qualcomm, Inc.
• Inventors: Ames, William, Wiedeman, Robert A., Monte, Paul A., Carter, Stephen S.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): VINCENT, DAVID ROBERT
• Application Number:
  US08/778,882
• Time in Patent Office: 627 Days
• Field of Search: 370/316, 370/320-328, 455/427-430, 455/12.1-13.4, 455/98, 342/352-358
• US Class Current: 370/316
• CPC Class Codes: H04B 7/18534 for enhancing link reliablility, e.g. satellites diversity
• CPC Class Codes: H04B 7/18539 Arrangements for managing radio, resources, i.e. for establishing or releasing a connection
• CPC Class Codes: H04B 7/18541 for handover of resources

Abstract

A communication system (10), and a method executed by same, for allocating communications traffic through a plurality of satellites (12) of a constellation of low earth orbit satellites. Each of the plurality of satellites is oriented, at any given time when in view of a ground station (18), at a particular elevation angle. The method comprises the steps of: (a) providing each of the plurality of satellites with a receiver for receiving communication links from the ground station and a transmitter for transmitting communication links to user terminals; (b) in response to a request for service, determining if a highest elevation angle satellite can be assigned a new communications link; (c) if yes, assigning a new communication link to the highest elevation angle satellite; (d) if no, determining if a second highest elevation angle satellite can be assigned a new communications link; and (e) if yes, assigning a new communication link to the second highest elevation angle satellite. A number of different criteria can be employed in determining if a satellite can be assigned a new communication link, including: determining if the associated satellite has already been assigned a predetermined maximum number of communication links; and determining if the associated satellite, or a particular beam, is transmitting at or near to a power level that corresponds to a maximum peak flux density at the surface of the earth. Each of the steps of assigning is preferably accomplished such that the communication link is simultaneously established through at least two of the satellites to provide for diversity reception at a user'"'"'s terminal (13).

Claims

1. A method for allocating communications traffic amongst a plurality of satellites of a constellation of low earth orbit satellites, each of the plurality of satellites being oriented, at any given time when in view of a user terminal, at a particular elevation angle, comprising the steps of:

providing each of the plurality of satellites with a receiver for receiving communication links from a ground station, transmitters for transmitting communication links to user terminals through frequency channels, receivers for receiving communication links from user terminals through the frequency channels, and a transmitter for transmitting communication links to the ground station;

in response to a request to one of assign a communication link to a user terminal or to handoff an already assigned communication link, determining if a highest elevation angle satellite can be assigned a new communications link;

if yes, assigning a new communication link to the highest elevation angle satellite;

if no, determining if a lower elevation angle satellite can be assigned a new communications link; and

if yes, assigning a new communication link to a lower elevation angle satellite;

wherein

the steps of determining each include a step of determining if the satellite will be in view of both the user terminal and the ground station for a predetermined period of time and, if not, the satellite is not accepted for being assigned the new communication link; and

wherein

the steps of determining are each also performed in accordance with a predicted communications traffic loading for the satellite.

2. A method as set forth in claim 1, wherein each of the steps of determining include the further steps of:

determining if the communication link is to be operated in a diversity mode;

if yes, determining if at least one next lower elevation angle satellite can be assigned a new communications link; and

if yes, also assigning the communication link to the next lower elevation angle satellite such that the communication link is simultaneously conducted through at least two of the satellites.

3. A method for allocating communications traffic amongst a plurality of satellites of a constellation of non-geosynchronous satellites, each of the plurality of satellites being oriented, at any given time when in view of a user terminal, at a particular elevation angle, comprising the steps of:

generating a request to assign a communication link to a user terminal;

in response to the generated request, operating a ground station to assign the communication link to at least two satellites that are selected as having the highest elevation angles relative to the user terminal, in accordance with at least a current satellite communications traffic loading and a predicted satellite communications traffic loading for each of the plurality of satellites that are in view of the user terminal and the ground station, so as not to exceed a maximum satellite communications traffic loading for a given one of the satellites; and

operating the user terminal so as to coherently combine a communication signal received from said at least two satellites over the assigned communication link.