Method and system for controlling uplink power in a satellite communication system using error leveling

• US 6,430,418 B1
• Filed: 06/19/2000
• Issued: 08/06/2002
• Est. Priority Date: 06/19/2000
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Stephens, Scott A., Wright, David A., Munoz, Michael S., Nivens, Dennis A., Caso, Gregory S.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Moore, James K
• Application Number:
  US09/596,344
• Time in Patent Office: 778 Days
• Field of Search: 455/69, 455/70, 455/522, 455/12.1, 455/427, 370/318, 370/319, 370/326, 370/321
• US Class Current: 455/522
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• 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 method and system for controlling uplink power in a satellite communication system using error leveling is provided. The uplink power control system for a satellite communication system of a preferred embodiment of the present invention comprises a communication satellite (101) and at least one UET (105). The communication satellite (101) includes an error detector (211) and a comparator (215). The UET (105) includes a receiver (206) for receiving an error indicator signal from the comparator (215), and a power profile processor (216) for controlling the transmit power level of the particular chanslot being used by the UET in response to the error indicator. A preferred method for controlling the transmit power level of a particular chanslot assigned to a UET in a satellite communication system in accordance with the present invention includes determining an error count for an uplink data signal received from the UET in the chanslot (403), and comparing the error count to a predetermined error threshold (404). The method further includes generating an error indicator signal for the chanslot in response to the comparison (405), and controlling the transmit power level of the particular chanslot in response to the error indicator (409, 410).

Claims

1. A method for controlling a transmit power level of a plurality of chanslots used by at least one user terminal in a satellite communication system, said method comprising the steps of:

comparing a predetermined error threshold to a number of errors in a data signal in a plurality of chanslots received at a satellite from at least one user terminal;

generating a plurality of error indicators, each error indicator corresponding to a related chanslot in use by a corresponding user terminal, wherein each of said error indicators is generated in response to said comparison; and

independently controlling a transmit power level of each of said chanslots at said corresponding user terminals in response to said corresponding error indicators.

2. A method for controlling a transmit power level of a plurality of chanslots used by a user terminal in a satellite communication system, said method comprising the steps of:

comparing a predetermined error threshold to a number of errors in a data signal in a plurality of chanslots received at a satellite from a user terminal;

generating a plurality of error indicators, each error indicator corresponding to a related chanslot in use by said user terminal, wherein each of said error indicators is generated in response to said comparison; and

independently controlling a transmit power level of each of said chanslots at said user terminal in response to said corresponding error indicators.

3. A method for controlling a transmit power level of a chanslot assigned to a user terminal in a satellite communication system, said method comprising the steps of:

performing an error count of a data signal transmitted from a user term to a satellite in a chanslot;

generating an error indicator in response to a comparison of a predetermined error threshold to said error count;

preparing an error report at said satellite in response to said error indicator, wherein said error report includes a plurality of error indicators, wherein each error indicator corresponds to a different chanslot;

transmitting said error report including said error indicator to said user terminal;

parsing said error report at said user terminal to extract said error indicator; and

controlling a transmit power level of said chanslot at said user terminal in response to said error indicator.

4. The method of claim 3 wherein said preparing step comprises the step of preparing said error report corresponding to a frame number and a slot number of said satellite communication system, in response to said error indicator.

5. The method of claim 3 wherein said error report is in the form of at least one Asynchronous Transfer Mode (ATM) cell.

6. The method of claim 3 wherein said parsing step comprises the steps of:

determining said frame number and said slot number to which said error report corresponds;

determining whether said chanslot is in said frame number and said slot number; and

controlling said transmit power level of said chanslot at said user terminal in response to said error indicator if said chanslot is in said frame number and said slot number.

7. The method of claim 6 wherein said controlling step further comprises the step of increasing or decreasing said transmit power level of said chanslot in response to said error indicator.

8. A method for controlling a transmit power level of a chanslot assigned to a user terminal in a satellite communication system, said method comprising the steps of:

performing an error count of a data signal transmitted from a user terminal to a satellite in a chanslot;

generating an error indicator in response to a comparison of a predetermined error threshold to said error count;

transmitting the error indicator to said user terminal; and

controlling a transmit power level of said chanslot at said user terminal in response to said error indicator,

wherein said generating step comprises the step of generating a multi-bit error indicator in response to said comparison where each value of said multi-bit error indicator corresponds to one of a plurality of predetermined ranges of ratios of said error count relative to said error threshold.

9. The method of claim 8 wherein said controlling step further comprises the step of controlling the transmit power level of said chanslot in response to said multi-bit error indicator by one of a plurality of predetermined amounts, wherein each of said predetermined ranges corresponds to one of said predetermined amounts.

10. A method for controlling a transmit power level of a plurality of chanslots used by at least one user terminal in a satellite communication system, said method comprising the steps of:

comparing a predetermined error threshold to a number of errors in a data signal in a plurality of chanslots received at a satellite from at least one user terminal;

generating a plurality of error indicators, each error indicator corresponding to a related chanslot in use by a corresponding user terminal, wherein each of said error indicators is generated in response to said comparison;

preparing an error report at said satellite in response to said plurality of error indicators, wherein said error report includes said plurality of error indicators;

parsing said error report at said at least one user terminal, wherein each individual user terminal extracts said error indicators that correspond to a related chanslot in use by said individual user terminals; and

independently controlling a transmit power level of each of said chanslots at said corresponding user terminals in response to said corresponding error indicators.

11. The method of claim 10 wherein said preparing step comprises the step of preparing said error report corresponding to a frame number and a slot number of said satellite communication system, in response to said error indicator signals.

12. The method of claim 11 wherein said error report is in the form of at least one Asynchronous Transfer Mode (ATM) cell.

13. A method for controlling a transmit power level of a chanslot assigned to a user terminal in a satellite communication system, said method comprising the step of:

transmitting an uplink data signal using a channel from a user terminal to a satellite;

receiving said data signal in said chanslot at said satellite;

determining an error count for said uplink data signal in said chanslot using said data signal received from said user terminal;

comparing said error count to a predetermined error threshold;

generating an error indicator for said chanslot in response to said comparing step;

transmitting said error indicator to said user terminal;

receiving said error indicator at said user terminal; and

controlling said transmit power level of said chanslot in response to said error indicator,

wherein said generating step comprises the step of generating a multi-bit error indicator in response to said comparing step where each value of said multi-bit error indicator corresponds to one of a plurality of predetermined ranges of ratios of said error count relative to said error threshold.

14. The method of claim 13 wherein said controlling step further comprises the step of controlling the transmit power level of said chanslot in response to said multi-bit error indicator by one of a plurality of predetermined amounts, wherein each of said predetermined ranges corresponds to one of said predetermined amounts.

15. A method for controlling a transmit power level of a chanslot assigned to a user terminal in a satellite communication system, said method comprising the step of:

transmitting an uplink data signal using a channel from a user terminal to a satellite;

receiving said data signal in said chanslot at said satellite;

determining an error count for said uplink data signal in said chanslot using said data signal received from said user terminal;

comparing said error count to a predetermined error threshold;

generating an error indicator for said chanslot in response to said comparing step;

preparing an error report at said satellite in response to said error indicator, wherein said error report includes a plurality of error indicators, wherein each error indicator corresponds to a different chanslot;

transmitting said error report including said error indicator to said user terminal;

receiving said error indicator at said user terminal;

parsing said error report at said user terminal to extract said error indicator; and

controlling said transmit power level of said chanslot in response to said error indicator.

16. The method of claim 15 wherein said preparing step comprises the step of preparing said error report corresponding to a frame number and a slot number of said satellite communication system, in response to said error indicator signal.

17. The method of claim 16 wherein said error report is in the form of an Asynchronous Transfer Mode (ATM) cell.

18. The method of claim 17 wherein said parsing step comprises the steps of:

determining said frame number and said slot number to which said error report corresponds;

determining whether said chanslot relates to said frame number and said slot number; and

controlling said transmit power level of said chanslot at said user terminal in response to said error indicator if said chanslot relates to said frame number and said slot number.

19. The method of claim 18 wherein said controlling step further comprises the step of increasing or decreasing said transmit power level of said chanslot in response to said error indicator.

20. A satellite communication system comprising:

a communication satellite including;

an error detector for determining the error count in a received data signal transmitted from a user terminal to said communication satellite using a chanslot;

a comparator for generating an error indicator in response to a comparison of said error count to a predetermined error threshold;

error report circuit for preparing an error report at said satellite in response to said error indicator, wherein said error report includes a plurality of error indicators, wherein each error indicator corresponds to a different chanslot; and

a transmitter for transmitting said error report including said error indicator to a user terminal; and

a user terminal including;

a receiver for receiving said error indicator from said comparator; and

a power profile processor for controlling a transmit power level of said chanslot in response to said error indicator.

21. The satellite communication system of claim 20 further comprising an error report processor for parsing said error report at said user terminal to extract said error indicator.

22. A user terminal for use in a satellite communication system comprising:

a receiver for receiving an error indicator for a chanslot from a communication satellite, said error indicator determined by comparing a predetermined error threshold to an error count in a received data signal transmitted from said user terminal to said communication satellite using said chanslot;

an error report processor for parsing an error report received by said user terminal to extract said error indicator from said error report, wherein said error report includes a plurality of error indicators, wherein each error indicator corresponds to a different chanslot; and

a power profile processor for controlling a transmit power level of said chanslot of said user terminal in response to said error indicator.

23. A satellite for use in a satellite communication system comprising:

an error detector for determining the error count in a received data signal transmitted from a user terminal to said satellite using a chanslot;

a comparator for generating an error indicator in response to a comparison of said error count to a predetermined error threshold, said error indicator to be used by said user terminal for controlling a transmit power level of said chanslot assigned to said user terminal in response to said error indicator; and

an error report circuit for preparing an error report at said satellite in response to said error indicator, wherein said error report includes a plurality of error indicators, wherein each error indicator corresponds to a different chanslot.