Method and system of tracking dynamic communication parameters during a link interruption

• US 5,937,349 A
• Filed: 10/29/1996
• Issued: 08/10/1999
• Est. Priority Date: 10/29/1996
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Andresen, Michael J.
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/740,455
• Time in Patent Office: 1,015 Days
• Field of Search: 455/427, 455/428, 455/429, 455/431, 455/441, 455/437, 455/11.1, 455/13.1, 370/316
• US Class Current: 455/431
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185

Abstract

In a dynamic communication system (90) wherein communication parameters vary appreciably between transmissions, mobile subscriber units (200) are susceptible to link blockages resulting in a loss of successive feedback instructing subscriber units (200) of adjustments to communication parameters to be employed in a subsequent transmission on a communication link (105). When a mobile subscriber unit (200) is airborne, an outage may occur from a control surface blockage during maneuvering. Aircraft avionics (290) supplies acceleration data representing aircraft movement for use in predicting subsequent communication parameters. A method and system are employed to predict subsequent communication parameters and employ these predictions during link blockages in an attempt to reestablish communications and upon the removal of a link blockage, a mobile subscriber unit (200) employs the predicted communication parameters to resume communications.

Claims

1. In a wireless communication system, a method of restoring a communication link between a mobile base station and a mobile subscriber unit following an interruption of said communication link comprising the steps of:

establishing said communication link having dynamic communication parameters;

revising said dynamic communication parameters as orientation changes between said mobile base station and said mobile subscriber unit;

upon an interruption of said communication link, providing acceleration data characteristic of said mobile subscriber unit;

said mobile subscriber unit producing predicted communication parameters in part from said acceleration data;

attempting to restore said communication link using said predicted communication parameters;

determining if said communication link has been restored; and

when said communication link has not been restored, repeating said producing step, said attempting step, and said determining step.

2. The method as recited in claim 1 further comprising the step of generating said acceleration data representative of motion of said mobile subscriber unit.

3. The method as recited in claim 1 wherein said revising step comprises the steps of:

transmitting on said communication link using said dynamic communication parameters;

evaluating at said mobile base station an accuracy of said dynamic communication parameters employed by said mobile subscriber unit;

when said accuracy of said dynamic communication parameters exceeds a threshold, transmitting feedback communication parameters denoting adjustments to said dynamic communication parameters to said mobile subscriber unit;

receiving said feedback communication parameters; and

employing said feedback communication parameters to generate said dynamic communication parameters for use in subsequent transmissions by said mobile subscriber unit.

4. The method as recited in claim 3 wherein said employing step further comprises the steps of:

when said mobile subscriber unit receives feedback communication parameters, incorporating said feedback communication parameters into said dynamic communication parameters; and

else generating dynamic communication parameters from previous ones of said dynamic communication parameters.

5. The method as recited in claim 4 further comprising the step of employing a Kalman-type filter in said incorporating and generating steps.

6. The method as recited in claim 1 wherein said predicting step further comprises the steps of:

filtering previous ones of said dynamic communication parameters;

incorporating said acceleration data; and

predicting current dynamic communication parameters.

7. The method as recited in claim 6 further comprising the step of attempting to reestablish said communication link using said current dynamic communication parameters as said dynamic communication parameters.

8. The method as recited in claim 6 further comprising the step of employing a Kalman-type filter for performing said filtering steps.

9. The method as recited in claim 1 further comprising the steps of employing Doppler frequency offset and propagation delay as said dynamic communication parameters.

10. The method as recited in claim 1 wherein said mobile base station is an orbiting satellite and said mobile subscriber unit is aboard an aircraft.

11. In a wireless communication system, a method of resuming communication services in a mobile subscriber unit upon an interruption of a communication link between a mobile base station and said mobile subscriber unit comprising the steps of:

establishing said communication link using dynamic communication parameters;

revising said dynamic communication parameters as orientation changes between said mobile base station and said mobile subscriber unit;

upon an interruption of said communication link, receiving acceleration data characteristic of said mobile subscriber unit;

producing predicted communication parameters in part from said acceleration data;

attempting to restore said communication link using said predicted communication parameters;

determining if said communication link has been restored; and

when said communication link has not been restored, repeating said producing step, said attempting step, and said determining step.

12. The method as recited in claim 11, wherein prior to the step of establishing said communication link, said method further comprises the steps of:

receiving initial values of said dynamic communication parameters at said mobile subscriber unit; and

employing said initial values of said dynamic communication parameters in said establishing step.

13. The method as recited in claim 11, wherein said revising step comprises the steps of:

transmitting on said communication link using said dynamic communication parameters;

when said dynamic communication parameters exceeds a tolerance for said dynamic communication parameters, receiving from said mobile base station feedback communication parameters; and

employing said feedback communication parameters to generate said dynamic communication parameters for use in subsequent transmissions.

14. The method as recited in claim 11, wherein said method further comprises the steps of:

when said mobile subscriber unit receives feedback communication parameters, incorporating said feedback communication parameters into said dynamic communication parameters; and

else generating dynamic communication parameters from previous ones of said dynamic communication parameters.

15. The method as recited in claim 14 further comprising the step of employing a Kalman-type filter in said incorporating and generating steps.

16. The method as recited in claim 11, wherein said predicting step further comprises the steps of:

filtering previous ones of said dynamic communication parameters;

incorporating said acceleration data; and

predicting current dynamic communication parameters.

17. The method as recited in claim 16 further comprising the step of attempting to reestablish said communication link using said current dynamic communication parameter as said dynamic communication parameters.

18. A method as recited in claim 16 further comprising the step of employing a Kalman-type filter for performing said filtering steps.

19. A method as recited in claim 11 further comprising the steps of employing Doppler frequency offset and propagation delay as said dynamic communication parameters.

20. A method as recited in claim 11 wherein said mobile base station is an orbiting satellite and said mobile subscriber unit is aboard an aircraft.

21. A mobile subscriber unit for resuming communication services upon interruption of a communication link with a mobile base station, comprising:

a receiver for receiving feedback communication parameters from said mobile base station, said feedback communication parameters being determined from previous transmissions on said communication link by said mobile base station;

a transmitter for cooperatively establishing said communication link by employing dynamic communication parameters;

a controller for extracting said feedback communication parameters from said receiver;

a communication parameter predictor for receiving from said controller said feedback communication parameters and predicting from said feedback communication parameters and from previous ones of said dynamic communication parameters, present ones of said dynamic communication parameters, said communication parameter predictor also receiving acceleration data from an avionics source upon interruption of said communication link; and

a synthesizer for revising said transmitter and said receiver according to said dynamic communication parameters for a subsequent interaction on said communication link.