Uplink power control system for satellite communication system employing on-board satellite processing and fade estimation

• US 20030040274A1
• Filed: 06/06/2001
• Published: 02/27/2003
• Est. Priority Date: 06/06/2001
• Status: Active Grant

• Current Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Original Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Inventors: Antia, Yezdi, Kay, Stan, Shi, Zhenliang, Khan, Anwer, Dai, Jerry, Zakaria, Gaguk
• Granted Patent: US 7,043,199 B2
• Time in Patent Office: Days
• US Class Current: 455/13.4
• 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

An uplink power control system for terminals in a satellite communication system provides closed loop power control using feedback signals generated at a satellite. The satellite performs inter-beam routing of uplink signals from satellite terminals, and processing of uplink signals to generate terminal transmission-specific feedback information that is transmitted in downlink signals to the terminals. The satellite also generates a beacon signal. An uplink power control algorithm at each terminal uses the beacon signal and feedback data to adjust transmit power.

Claims

1. An uplink power control system for terminals in a satellite communication system comprising:

a satellite terminal operable to transmit uplink signals to and receive downlink signals from a satellite and comprising a programmable processing device, said downlink signals comprising feedback power data generated at said satellite in response to said uplink signals; and

a power control module operating with said processing device to adjust transmit power for said uplink signals in accordance with said feedback power data.

2. An uplink power control system as claimed in claim 1, wherein said power control module is operable to adjust said transmit power per carrier frequency used by said satellite terminal to transmit said uplink signals.

3. An uplink power control system as claimed in claim 1, wherein said power control module is operable to maintain and update data relating to the uplink spectrum comprising the satellite terminal transmit spectrum, the satellite receive spectrum and atmospheric attenuation, and to adjust said transmit power using said data.

4. An uplink power control system as claimed in claim 3, wherein said power control module controls said terminal to automatically transmit a periodic calibration signal to said satellite after a time period of selected duration has elapsed since said terminal transmitted one of said uplink signals in response to a user request, said feedback power data generated in response to said calibration signal and transmitted via said downlink signals being used by said terminal to update said data relating to said uplink spectrum.

5. An uplink power control system as claimed in claim 4, wherein said data relating to said uplink spectrum indicating system variations comprising at least one of terminal temperature variation and satellite gain-to-temperature variation.

6. An uplink power control system as claimed in claim 1, wherein said power control module is operable to maintain and update data relating to the shape of the uplink spectrum comprising the satellite terminal transmit spectrum and the satellite receive spectrum, and to adjust said transmit power using said data.

7. An uplink power control system as claimed in claim 1, wherein said downlink signals comprise a beacon signal, said power control module being operable to determine carrier to noise or C/N data using said beacon signal, to maintain and update fade data relating to estimated uplink fade using said C/N data, and to adjust said transmit power using said fade data.

8. An uplink power control system as claimed in claim 1, wherein said downlink signals comprise a beacon signal, said power control module being operable to determine carrier to noise or C/N data using said beacon signal, to maintain and update fade data relating to estimated uplink fade using said C/N data, to maintain and update spectrum data relating to the uplink spectrum comprising the satellite terminal transmit spectrum and the satellite receive spectrum, and to adjust said transmit power using said fade data and said spectrum data.

9. An uplink power control system as claimed in claim 8, wherein said spectrum data comprises at least one of an estimated shape of said uplink spectrum and changes in the amplitude of said uplink spectrum.

10. An uplink power control system as claimed in claim 8, wherein said spectrum data comprises an estimated shape of said uplink spectrum and changes in the amplitude of said uplink spectrum.

11. An uplink power control system as claimed in claim 8, wherein said downlink signal comprises an uplink power control status packet generated at said satellite for said terminal, said status packet comprising signal to noise ratio data corresponding to a frequency channel in said satellite communication channel on which said uplink signals are being transmitted, and further comprising a storage device for storing a plurality of filter tables for storing said fade data and said spectrum data, said power control module being operable to update said filter tables when said status packet is received.

12. An uplink power control system as claimed in claim 1, wherein said downlink signal comprises an uplink power control status packet generated at said satellite for said terminal, said status packet comprising signal to noise ratio data corresponding to a frequency channel in said satellite communication system on which said uplink signals are being transmitted.

13. An uplink power control system as claimed in claim 12, wherein said status packet further comprises data relating to the noise floor measured at said satellite.

14. An uplink power control system as claimed in claim 12, wherein said signal to noise data comprises signal-to-noise-and-interference measured at said satellite.

15. A method for performing uplink power control for terminals in a satellite communication system comprising the steps of:

assigning a communication channel to a terminal for transmitting an uplink signal to a satellite;

processing said uplink signals at said satellite to obtain signal to noise data corresponding to said communication channel;

generating a feedback signal corresponding said uplink signal on said channel; and

transmitting said feedback signal to said terminal.

16. A method as claimed in claim 15, further comprising the step of adjusting transmit power at said terminal in accordance with said feedback signal.

17. A method as claimed in claim 16, wherein said adjusting step comprises the step of updating fade data relating to fade conditions estimated using said feedback signal, said fade data being stored in a computer-readable medium at said terminal and used to adjust said transmit power.

18. A method as claimed in claim 17, wherein said updating step further comprises updating spectrum data stored in said computer-readable medium, said spectrum data relating to the uplink spectrum comprising terminal transmit spectrum, satellite receive spectrum and atmospheric attenuation, and used with said fade data to adjust said transmit power.

19. A method as claimed in claim 18, further comprising the steps of:

transmitting a periodic calibration signal to said satellite after a time period of selected duration has elapsed since said terminal transmitted a subsequent said uplink signal in response to a user request;

generating said feedback signal in response to said calibration signal;

transmitting said feedback signal to said terminal;

updating said data relating to the uplink spectrum in accordance with said feedback signal.

20. A method as claimed in claim 19, wherein said data relating to the uplink spectrum indicates system variations comprising at least one of terminal temperature variation and satellite gain-to-temperature variation.

21. A method as claimed in claim 18, further comprising the step of generating feedback data using said feedback signal to select said transmit power for a subsequent said uplink signal, said feedback data corresponding to said channel of the preceding said uplink signal and comprising selected said fade data and selected said spectrum data.

22. A method as claimed in claim 15, wherein said generating step comprises the steps of:

determining at least one of noise, signal-to-noise ratio and signal-to-noise-and-interference ratio of one of said uplink signals at said satellite;

generating a status signal indicating at least one of noise, signal-to-noise ratio and signal-to-noise-interference ratio corresponding to said uplink signal; and

transmitting said status signal to said terminal, said status signal being used by said terminal to determine said transmit power.

23. A method as claimed in claim 22, wherein said terminal transmits said uplink signals at a selected data rate, and further comprising the step of determining whether said terminal should enter a fallback mode during which said terminal transmits said uplink signals at a lower data rate depending on said status signal.

24. A method as claimed in claim 15, wherein said terminal transmits said uplink signals at a selected data rate, and further comprising the step of determining whether said terminal should enter a fallback mode during which said terminal transmits said uplink signals at a lower data rate when said feedback signal indicates excess attenuation due to rain.

25. A method as claimed in claim 24, wherein said terminal quits said fallback mode and resumes transmitting said uplink signals at a higher data rate than said lower data rate when said feedback signal no longer indicates said attenuation.

26. A method as claimed in claim 15, wherein said generating step comprises the step of generating a uplink power control status packet generated at said satellite for said terminal, said status packet comprising signal to noise ratio data corresponding to said channel on which said uplink signals are being transmitted.

27. An uplink power control system as claimed in claim 26, wherein said status packet further comprises data relating to the noise floor measured at said satellite.

28. An uplink power control system as claimed in claim 26, wherein said signal to noise data comprises signal-to-noise interference data measured at said satellite.

29. An uplink power control system for terminals in a satellite communication system comprising:

a satellite transceiver device operable to receive uplink signals to and transmit downlink signals to a terminal comprising a programmable processing device; and

a power control module operating with said processing device to generate feedback power data in response to said uplink signals, and to transmit said feedback power data via said downlink signals, said terminal adjusting its transmit power for said uplink signals in accordance with said feedback power data.

30. An uplink power control system as claimed in claim 29, wherein said power control module is operable to generate a beacon signal, said terminal being operable to determine a carrier-to-noise ratio for said beacon signal to facilitate adjusting said transmit power.

31. An uplink power control system as claimed in claim 29, wherein said uplink signals are assigned different channels in said satellite communication system, said feedback power data comprising an uplink status packet generated at said satellite and comprising at least one of signal to noise ratio data corresponding to said channel, data relating to the noise floor measured at said satellite, and signal-to-noise interference data measured at said satellite, and channel identification data to allow said terminal to determine that said status packet corresponds to said uplink signal from which the data for said uplink status packet was measured.