Granted Patent B2

US 8,335,468 · App. 12/946,492 · Granted Dec 18, 2012

Abstract

Claims (49)

1. A method for interference cancellation in a satellite communication system, the method comprising:

(a) transmitting a hub signal from a first station to a second station via satellite;

(b) receiving a hub echo signal in the first station;

(c) in a computing device, performing an autocorrelation on the hub signal to detect a periodicity in the hub signal;

(d) if the periodicity is detected, determining, in the computing device, a search range for a delay in the hub echo signal in accordance with the periodicity;

(e) locating the delay in the hub echo signal, using the computing device; and

(f) in the computing device, performing the interference cancellation in accordance with the delay located in step (e).

2. The method of claim 1 , wherein step (d) comprises determining the search range for the delay in accordance with the periodicity detected in step (c) and an estimated satellite round-trip delay of the first station.

3. The method of claim 1 , wherein, if the periodicity is not detected, the search range for the delay is set to a default range.

4. The method of claim 1 , wherein the delay is located a plurality of times for a plurality of successively higher sampling rates.

5. The method of claim 4 , wherein the plurality of successively higher sampling rates comprises a sampling rate that is higher than a signal bandwidth of the hub signal.

6. The method of claim 1 , further comprising determining a Doppler value, and wherein step (d) comprises determining a search range for the Doppler value in accordance with the periodicity.

7. The method of claim 6 , wherein:

the delay is located a plurality of times for a plurality of successively higher sampling rates; and

for a lowest one of the sampling rates, a fine Doppler value and coarse delay are determined.

8. The method of claim 7 , wherein the plurality of successively higher sampling rates comprises a sampling rate that is higher than a signal bandwidth of the hub signal.

9. The method of claim 1 , further comprising:

(g) monitoring the autocorrelation performed in step (c);

(h) from the monitoring performed in step (g), detecting a change in either the periodicity or a periodic-to-aperiodic ratio of the hub signal; and

(h) when the change exceeds a threshold, re-acquiring the hub signal and performing steps (c)-(f) in accordance with the re-acquired hub signal.

10. A system for interference cancellation in a satellite communication system, the system comprising:

a communication component for transmitting a hub signal to a remote station via satellite and for receiving a hub echo signal; and

a computing device, in communication with the communication component, the computing device configured for:

performing an autocorrelation on the hub signal to detect a periodicity in the hub signal;

if the periodicity is detected, determining a search range for a delay in the hub echo signal in accordance with the periodicity;

locating the delay in the hub echo signal; and

performing the interference cancellation in accordance with the delay.

11. The system of claim 10 , wherein the computing device is configured for determining the search range for the delay in accordance with the periodicity and an estimated satellite round-trip delay.

12. The system of claim 10 , wherein the computing device is configured such that, if the periodicity is not detected, the search range for the delay is set to a default range.

13. The system of claim 10 , wherein the computing device is configured such that the delay is located a plurality of times for a plurality of successively higher sampling rates.

14. The system of claim 13 , wherein the computing device is configured such that the plurality of successively higher sampling rates comprises a sampling rate that is higher than a signal bandwidth of the hub signal.

15. The system of claim 10 , wherein the computing device is further configured for determining a Doppler value and for determining a search range for the Doppler value in accordance with the periodicity.

16. The system of claim 15 , wherein the computing device is configured such that:

the delay is located a plurality of times for a plurality of successively higher sampling rates; and

for a lowest one of the sampling rates, a fine Doppler value and coarse delay are determined.

17. The system of claim 16 , wherein the computing device is configured such that the plurality of successively higher sampling rates comprises a sampling rate that is higher than a signal bandwidth of the hub signal.

18. The system of claim 10 , wherein the computing device is further configured for:

monitoring the autocorrelation;

from the monitoring, detecting a change in either the periodicity or a periodic-to-aperiodic ratio of the hub signal; and

when the change exceeds a threshold, re-acquiring the hub signal and performing the operations of performing the autocorrelation through performing the interference cancellation in accordance with the re-acquired hub signal.

19. An article of manufacture for interference cancellation in a satellite communication system, the article of manufacture comprising:

a machine-readable tangible persistent storage medium; and

code stored on the medium, the code, when executed on a computing device, controlling the computing device for:

(a) transmitting a hub signal from a first station to a second station via satellite;

(b) receiving a hub echo signal in the first station;

(c) performing an autocorrelation on the hub signal to detect a periodicity in the hub signal;

(d) if the periodicity is detected, determining a search range for a delay in the hub echo signal in accordance with the periodicity;

(e) locating the delay in the hub echo signal; and

(f) performing the interference cancellation in accordance with the delay located in step (e).

Assignments (15)