Channel frequency allocation for multiple-satellite communication network

• US 6,021,309 A
• Filed: 05/22/1997
• Issued: 02/01/2000
• Est. Priority Date: 05/22/1997
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated, Loral Aerospace Corp. (MHR Holdings LLC (New York))
• Original Assignee: Globalstar Incorporated
• Inventors: Sherman, Richard H., Driggers, Theodore F.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): NGUYEN, DUC M
• Application Number:
  US08/861,891
• Time in Patent Office: 985 Days
• Field of Search: 455/12.1, 455/13.1, 455/13.2, 455/13.3, 455/13.4, 455/450, 455/447, 455/451, 455/452, 455/427, 455/509, 455/101
• US Class Current: 455/12.1
• 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 7/18543 for adaptation of transmission parameters, e.g. power control for detecting or preventing errors in the information received H04L1/00
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

A method and apparatus (system) for providing forward-link channel-frequency allocation for multiple-satellite cellular communications networks is disclosed. The system has a centralized ground-operations control center that provides bi-weekly minute-by-minute allocation plans for geographically-defined service areas. This enables each service area to set its diversity policy in accordance with the requirements of the government regulators and customer preferences within the service area. The system has a user model having a frequency re-use pattern, a channel allocation model for modelling the power allocated to each channel, and a gateway channel model for allocating channels in accordance with the user model and the channel allocation model. The allocation is made for each satellite of the plurality of satellites. The traffic allocation induces an operating frequency for each of the one or more links in each satellite of the plurality of satellites. The satellite communication system computed frequency allocation is optimized to minimize total radiation from all forward links for one or more of the plurality of satellites.

Claims

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

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

one or more terrestrial gateways, said gateways being linked to one or more satellites in said constellation for carrying said traffic, each of said gateways associated with a geographically limited cell;

a computing center, operatively associated with said communication system; and

a communication link allocation system within said computing center for calculating optimized available resources and for allocating said traffic according to said optimized resources for a specific cell, said communication link allocation system comprising;

a first computer module constructed to generate and store a geographic definition of a cell including the communications resources available thereto and the power constraints related to said resources;

a second computer module constructed to generate and store a user traffic model based on historic user demands related to said cell over time, including data relating to channel changes for connected links;

a third computer module constructed to generate and store an optimized performance objective in the form of a barrier function which penalizes allocations which cause channel changes to links in said cell over time; and

wherein said communication link allocation system calculates a solution for optimum traffic allocation for traffic within a cell at a particular time, at least in part based on said data in said first, second, and third computer modules; and

a traffic allocation module comprising;

a tiling module for defining multiple subdivisions within said cell;

a diversity implementation module for receiving and storing a selected diversity policy; and

a subdivision adjustment section for adjusting the definition of a subdivision in accordance with said diversity policy and said user traffic model, thereby balancing the signal to noise ratio among links in said cell.

2. A satellite communication system operative with at least one existing terrestrial communication system for carrying communication traffic, as described in claim 1 wherein said tiling module defines said subdivision to maximize the distance between subdivisions in which a specific channel is reused.

3. A satellite communication system operative with at least one existing terrestrial communication system for carrying communication traffic, as described in claim 1 wherein a channel is assigned to each subdivision.

4. A satellite communication system operative with at least one existing terrestrial communication system for carrying communication traffic, as described in claim 1 wherein the diversity implementation module selects a diversity policy from diversity control policies including, completely shared channels, completed partitioned channels, or hybrids thereof.

5. In a satellite communication system operative with at least one existing terrestrial communication system, said communication system comprising a constellation 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, a method of allocating communications traffic comprising the steps of:

generating and storing a geographic definition of a cell including the communications resources available thereto and the power constraints related to said resources;

generating and storing a user traffic model based on historic user demands related to said cell over time, including data relating to channel changes for connected links within a cell overtime; and

generating and storing an optimized performance objective in the form of a barrier function which penalizes allocations which cause excessive channel changes to links in said a cell over time; and

calculating a solution for optimum traffic allocation for traffic within a cell at a particular time, at least in part based on said data generated and stored in said prior steps;

defining multiple subdivisions within said cell;

receiving and storing a selected diversity policy; and

adjusting the definition of a subdivision in accordance with said diversity policy and said user traffic model, thereby balancing the signal to noise ratio among links in said cell.

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, a method of allocating communications traffic as described in claim 5 wherein the step of calculating a solution for optimum traffic allocation for traffic within a cell at a particular time, includes selecting a channel reuse diversity policies, including;

completely shared channels, completed partitioned channels, or hybrids thereof.

7. 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, a method of allocating communications traffic as described in claim 5 wherein said subdivision is defined to maximize the distance between subdivisions in which a specific channel is reused.

8. 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, a method of allocating communications traffic as described in claim 5 wherein said step of defining multiple subdivisions within said cell includes assigning a specific communications channel to each subdivision.