Multiple satellite system power allocation by communication link optimization

• US 6,091,933 A
• Filed: 01/03/1997
• Issued: 07/18/2000
• Est. Priority Date: 01/03/1997
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated, Loral Aerospace Corp. (MHR Holdings LLC (New York))
• Original Assignee: Globalstar Incorporated
• Inventors: Huang, John J. Y., Gallagher, Vijaya, Sherman, Richard H.
• Primary Examiner(s): Le, Thanh Cong
• Assistant Examiner(s): Armstrong, Darnell R.
• Application Number:
  US08/778,908
• Time in Patent Office: 1,292 Days
• Field of Search: 455/427, 455/453, 455/432, 455/12.1, 455/13.1, 455/13.4, 455/522, 455/504, 455/506, 455/560
• US Class Current: 455/13.1
• CPC Class Codes: H04B 7/18534 for enhancing link reliablility, e.g. satellites diversity
• CPC Class Codes: H04B 7/18543 for adaptation of transmission parameters, e.g. power control for detecting or preventing errors in the information received H04L1/00

Abstract

A satellite communications system is described. The system includes a plurality of satellites, each of which transmits one or more forward links containing traffic to one or more terrestrial users. Each forward link of each of the satellites has a maximum radiation limit. At least one terrestrial user is capable of concurrently receiving at least two of the forward links. The concurrently received forward links redundantly contain the traffic addressed to the user. A computing center has a traffic controller for allocating the traffic to the satellites using gateways. The traffic controller includes a fading model descriptive of fading characteristics for each of the one or more forward links; a link performance model descriptive of losses in each of the forward links; and a power allocation model for computing a traffic allocation for each satellite of the constellation of satellites. The traffic allocation causes transmitted satellite power to be less than the maximum radiation limit for each link. The traffic control system may be located within a gateway so as to optimize traffic associated with that gateway alone. The optimization may also be directed to minimize total radiation from all forward links for particular satellites.

Claims

1. A satellite communications system operative with at least one existing terrestrial communication system for carrying communications traffic, comprising:

a plurality of satellites in earth orbit, each of said satellites transmitting one or more forward links containing said traffic to one or more terrestrial users,

one or more terrestrial gateways, said gateways being bidirectionally linked to one or more satellites of said plurality of satellites for carrying said traffic;

a computing center, linked to said gateways; and

a communication link allocation system for calculating optimized available resources and for allocating said traffic according to said optimized resources, said communication link allocation system comprising;

first means to generate and store a fading model descriptive of fading characteristics for each of said one or more forward links;

second means to generate and store a link performance model descriptive of losses in each of said one or more forward links including said fading model; and

third means to generate and store a power allocation model based on power constraints for each satellite and said fading model and said link performance model, said third means computing a traffic allocation solution based on said models which allows said communication link allocation system to allocate traffic in accordance therewith.

2. The satellite communication system of claim 1, wherein said traffic control means is part of one or more of said gateways.

3. The satellite communication system of claim 1, wherein said traffic control means is part of said computing center, and wherein traffic allocation results output from said traffic control means are transmitted to said gateways.

4. The satellite communication system of claim 1, wherein said traffic allocation is optimized to minimize total radiation from all forward links for one or more of said plurality of satellites.

5. The satellite communication system of claim 1, wherein said traffic allocation results in downlink radiation for each of said one or more links in each satellite of said plurality of satellites, said radiation being less than said maximum radiation limit for each of said one or more links.

6. In a satellite communication system operative with at least one existing terrestrial communication system, said communication system comprising a plurality of satellites, a plurality of terrestrial user terminals, and at least one terrestrial gateway for establishing communication links between the user terminals and the terrestrial communication system via one or more of the satellites, and further comprising a communications link allocation system, a method of allocating communications traffic comprising the steps of:

computing a fading model descriptive of fading characteristics in each of said one or more communication links;

computing a link performance model including said fading model descriptive of losses in each of said one or more forward links;

computing a power allocation model based on power constraints for each satellite and said fading model and said link performance model, and

computing a traffic allocation solution based on said models which allows said communication link allocation system to allocate traffic in accordance therewith.

7. A method as set forth in claim 6, wherein the communications link allocation system is located apart from the at least one gateway, and further comprising a step of transferring the traffic allocation solution to the at least one gateway.

8. A method as set forth in claim 6, wherein the power allocation model includes an interference model, including a gateway-to-gateway interference model, a satellite-to-satellite interference model, and a beam-to-beam interference model.

9. A method as set forth in claim 6, wherein the communications traffic is allocated so as to provide links though a plurality of satellites for individual ones of the user terminals.

10. A method of allocating communications traffic as described in claim 6, wherein the constraint information includes information descriptive of satellite battery usage, satellite orbital geometry, power objectives and constraints, average outage probability, and future traffic projections.