INTERFERENCE RESISTANT SATELLITE LINK POWER CONTROL USING DOWNLINK BEACON

• US 20110007646A1
• Filed: 07/07/2010
• Published: 01/13/2011
• Est. Priority Date: 07/08/2009
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Irvine, David, Miller, Mark J.
• Granted Patent: US 8,385,223 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

A method for determining EIRP of user terminals in a satellite communication system comprises obtaining a frequency gain of a gateway at one or more frequencies, obtaining a path gain of the gateway for one or more signal paths, and obtaining a satellite beacon signal power at a receiver of the gateway. The method also comprises determining a target signal power at the gateway for one or more frequency channels, where the target signal power based at least in part on the frequency gain, the path gain, and the satellite beacon signal power. The method also comprises obtaining a message signal power at the gateway of a message from a user terminal, and determining the EIRP of the user terminal based at least in part on a difference between the target signal power and the message signal power.

Claims

1. A method for determining effective isotropic radiated power (EIRP) of user terminals in a satellite communication system, the method comprising:

obtaining a frequency gain of a gateway at one or more frequencies;

obtaining a path gain of the gateway for one or more signal paths;

obtaining a satellite beacon signal power at a receiver of the gateway;

determining a target signal power at the gateway for one or more frequency channels, the target signal power based at least in part on the frequency gain, the path gain, and the satellite beacon signal power;

obtaining a message signal power at the gateway of a message from a user terminal; and

determining the EIRP of the user terminal based at least in part on a difference between the target signal power and the message signal power.

2. The method of claim 1 further comprising obtaining an automatic gain control of one or more demodulators at the gateway.

3. The method of claim 1 wherein the target signal power is based at least in part on the frequency gain, the path gain, the satellite beacon signal power, and an automatic gain control of a demodulator at the gateway.

4. The method of claim 1 further comprising:

obtaining a target EIRP density of a return downlink;

obtaining an EIRP of a satellite beacon;

obtaining a rain fade level of the return downlink; and

obtaining an automatic gain control of a demodulator at the gateway, wherein the target signal power is based on one or more of the frequency gain, the path gain, the satellite beacon signal power, the target EIRP density, the EIRP of the satellite beacon, the rain fade level, and the automatic gain control of the demodulator.

5. The method of claim 1 wherein the message signal power is provided by a demodulator at the gateway.

6. The method of claim 1 wherein the path gain is a gain of one or more signal paths at the gateway between at least a plurality of low noise amplifiers and a plurality of demodulators.

7. The method of claim 1 wherein the message from the user terminal is one of a plurality of messages from the user terminal sent at a specified rate.

8. The method of claim 1 wherein the frequency gain is based at least in part on an input power of a pilot tone and a measured power of the pilot tone at a demodulator.

9. The method of claim 1 wherein the path gain is based at least in part on an input power of a pilot tone, a measured power of the pilot tone at a demodulator, and an signal path of the pilot tone between an input of the pilot tone and the demodulator.

10. The method of claim 1 wherein the one or more frequency channels comprise a plurality of frequency channels, and the one or more frequencies for obtaining the frequency gain are located in frequency between adjacent frequency channels.

11. The method of claim 1 wherein determining the frequency gain includes determining, at each of the one or more frequencies, a difference between a gain at a specified frequency and a gain at a frequency associated with the satellite beacon.

12. A process for controlling power of return link transmissions in a satellite communications system, the process comprising:

determining a first signal power of a first message from a user terminal;

determining a first target signal power;

determining a first EIRP of the user terminal based at least in part on a difference between the first signal power of the first message and the first target signal power;

waiting a period of time; and

repeating the process by determining a second signal power of a second message from the user terminal, determining a second target signal power, and determining a second EIRP of the user terminal based at least in part on a difference between the second signal power of the second message and the second target signal power.

13. The process of claim 12 further comprising adjusting an EIRP of the user terminal based on the first EIRP and adjusting the EIRP of the user terminal based on the second EIRP.

14. The process of claim 12 wherein determining the first target signal power and determining the second target signal power comprise determining gateway calibration data and determining satellite beacon signal power.

15. The process of claim 12 wherein the first target signal power is based on a frequency gain of a gateway in the satellite communications system, a path gain of the gateway, a signal power of a satellite beacon at the gateway, a target EIRP density of a return downlink from a satellite to the gateway, an EIRP of the satellite beacon, a rain fade level of the return downlink, and an automatic gain control of a demodulator at the gateway.

16. An apparatus for determining effective isotropic radiated power (EIRP) of user terminals in a satellite communications system, comprising:

an obtaining module configured to;

obtain at least one of a frequency gain or a path gain of a pilot tone in a gateway;

obtain a satellite beacon signal power at the gateway; and

obtain a message signal power at the gateway of a message from a user terminal;

a determining module configured to;

determine a target signal power at the gateway based on at least one of the frequency gain, the path gain, or the satellite beacon signal power; and

determine the EIRP of the user terminal based at least in part on a difference between the message signal power and the target signal power.

17. The apparatus of claim 16 further comprising a sending module configured to send the EIRP to the user terminal.

18. The apparatus of claim 16 wherein the target signal power is based at least in part on the frequency gain, the path gain, or the satellite beacon signal power.

19. The apparatus of claim 16 wherein the obtaining module is further configured to:

obtain a target EIRP density of a return downlink;

obtain an EIRP of satellite beacon;

obtain a rain fade level of the return downlink; and

obtain an automatic gain control of a demodulator at the gateway.

20. The apparatus of claim 19 wherein the target signal power is based at least in part on the frequency gain, the path gain, the satellite beacon signal power, the target EIRP density, the EIRP of the satellite beacon, the rain fade level, and the automatic gain control of the demodulator.