Systems and methods for tracking power peaks of a signal

• US 8,055,278 B2
• Filed: 11/20/2008
• Issued: 11/08/2011
• Est. Priority Date: 11/20/2008
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Floser, Erling, Skärby, Ulf, Huss, Fredrik
• Primary Examiner(s): Shedrick; Charles
• Application Number:
  US12/274,808
• Publication Number:
  US 20100124936A1
• Time in Patent Office: 1,083 Days
• Field of Search: 455/456.5
• US Class Current: 455/456.5
• CPC Class Codes: H04W 56/004 compensating for timing error of reception due to propagation delay
• CPC Class Codes: H04W 60/00 Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 84/047 using dedicated repeater stations

Abstract

In one aspect, the invention provides a method for tracking a mobile terminal. In some embodiments, this method includes the following steps: receiving a signal transmitted from the mobile terminal; searching a primary search area for a signal associated with the mobile terminal; searching a secondary search area for a signal associated with the mobile terminal, wherein the secondary search area is larger than the primary search area; determining the strength of a signal associated with the mobile terminal that was found by searching the secondary search area; and determining whether the primary search area should be modified based on the determined strength of the signal that was found by searching the secondary search area.

Claims

1. A method for tracking a mobile terminal, comprising:

receiving, at a first point in time, a direct signal transmitted from the mobile terminal, wherein the first point in time falls within a primary signal tracking window;

receiving, at a second point in time, a reflected signal corresponding to the direct signal, wherein the second point in time falls within a secondary signal tracking window and the reflected signal was transmitted by a repeater or relay in response to the repeater or relay receiving the direct signal;

determining a strength of the reflected signal; and

determining whether the primary signal tracking window should be modified based, at least in part, on the determined strength of the reflected signal.

2. The method of claim 1, further comprising modifying the primary signal tracking window in response to a determination that the strength of the reflected signal exceeds a threshold.

3. The method of claim 2, further comprising:

determining a strength of the direct signal;

comparing the strength of the direct signal to the strength of the reflected signal; and

modifying the primary signal tracking window in response to a determination that the strength of the reflected signal exceeds the strength of the direct signal.

4. The method of claim 3, wherein the step of modifying the primary signal tracking window comprises altering the primary signal tracking window so that the primary signal tracking window overlaps with the secondary signal tracking window.

5. The method of claim 4, wherein the step of altering the primary signal tracking window does not change the size of the primary signal tracking window.

6. The method of claim 2, wherein the step of modifying the primary signal tracking window comprises increasing the size of the primary signal tracking window.

7. The method of claim 6, wherein the size of the primary signal tracking window is increased so that the new primary signal tracking window overlaps with the secondary signal tracking window.

8. The method of claim 2, wherein the step of modifying the primary signal tracking window comprises creating a second primary signal tracking window.

9. The method of claim 8, further comprising searching the first and second primary signal tracking windows for a signal associated with the mobile terminal, wherein the second primary signal tracking window is smaller in size than the secondary signal tracking window.

10. The method of claim 1, further comprising:

sending a timing alignment value to the mobile terminal in response to a determination that the strength of the reflected signal exceeds a threshold.

11. The method of claim 1, wherein the secondary signal tracking window is used less frequently than the primary signal tracking window.

12. A base station, comprising:

a receiver configured to receive signals transmitted from a mobile terminal;

a processor configured to;

at a first point in time, receive a direct signal, via the receiver, that was transmitted by the mobile terminal, wherein the first point in time falls within a primary signal tracking window;

at a second point in time, receive a reflected signal, via the receiver, that corresponds to the direct signal, wherein the second point in time falls within a secondary signal tracking window and the reflected signal was transmitted by a repeater or relay in response to the repeater or relay receiving the direct signal;

determine a strength of the reflected signal; and

determine whether the primary signal tracking window should be modified based, at least in part, on the determined strength of the reflected signal.

13. The base station of claim 12, wherein the processor is further configured to modify the primary signal tracking window in response to a determination that the strength of the reflected signal exceeds a threshold.

14. The base station of claim 13, wherein the threshold is equal to a strength of the direct signal.

15. The base station of claim 13, wherein the processor is configured to modify the primary signal tracking window in response to said determination by altering the primary signal tracking window so that the primary signal tracking window overlaps with the secondary search area.

16. The base station of claim 15, wherein the processor is configured such that the altering of the primary signal tracking window does not change the size of the primary signal tracking window.

17. The base station of claim 13, wherein the processor is configured to modify the primary signal tracking window in response to said determination by increasing the size of the primary signal tracking window.

18. The base station of claim 17, wherein the processor is configured to increase the size of the primary signal tracking window so that the new primary signal tracking window overlaps with the secondary signal tracking window.

19. The base station of claim 13, wherein the processor is configured to modify the primary signal tracking window in response to said determination by creating a second primary signal tracking window.

20. The base station of claim 19, wherein the processor is configured to search the first and second primary signal tracking windows for a signal associated with the terminal, wherein the second primary signal tracking window is smaller in size than the secondary signal tracking window.

21. The base station of claim 12, wherein the processor is further configured to send a timing alignment value to the terminal in response to a determination that the strength of the reflected signal exceeds a threshold.

22. The base station of claim 12, wherein the processor is configured to use the secondary signal tracking window less frequently than the processor is configured to use the primary signal tracking window.

23. A base station, comprising:

a receiver for receiving signals transmitted from a terminal and reflected signals that have been transmitted by a relay or repeater and that correspond to signals transmitted from the terminal;

a terminal tracking module configured to search a primary search area for a signal associated with the terminal;

a secondary searching module configured to search a secondary search area for a reflected signal associated with the terminal, wherein the reflected signal was transmitted by a repeater or relay, wherein the secondary search area is larger than the primary search area;

a signal strength determining module configured to determine the strength of a reflected signal associated with the terminal that was found by searching the secondary search area;

a data processing module configured to determine whether the primary search area should be modified based on a determined strength of the reflected signal that was found by searching the secondary search area; and

a timing module configured to send a timing alignment value to the terminal in response to a determination that the strength of the reflected signal that was found by searching the secondary search area exceeds a threshold, wherein the timing alignment value corresponds to a delay associated with that reflected signal.