Method and apparatus for signal searching

• US 20080139127A1
• Filed: 11/08/2007
• Published: 06/12/2008
• Est. Priority Date: 11/08/2006
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Suwansantisuk, Watcharapan, Win, Moe Z.
• Granted Patent: US 8,565,690 B2
• Time in Patent Office: Days
• US Class Current: 455/67.16
• CPC Class Codes: H04B 1/7183 Synchronisation

Abstract

A method and corresponding apparatus for searching for a signal is presented. The apparatus may be configured to select a first bin within a range of bins characterizing an uncertainty region. The bins may represent a phase within a bandwidth of interest. The apparatus may also be configured to compare a local signal, having a phase corresponding to the first bin, with a received signal, the received signal being received via a transmission medium. The apparatus may report whether the local signal matches the received signal. The apparatus may assign weightings to the bins if the local signal does not match the received signal. If a match is not found, the apparatus may select a next bin according to the weightings or according to characteristic of the transmission medium until a matching bin is obtained. One benefit of the search is reduced search time to allow, for example, a cell phone to synchronize the phase of a received signal more quickly than is currently done.

Claims

1. A method for searching for a signal comprising:

selecting a first bin within a range of bins, each bin corresponding to a phase of a transmitted signal;

comparing a local signal, having a phase corresponding to the first bin, with a received signal, the received signal being received via a transmission medium;

reporting whether the local signal matches the received signal;

assigning weightings to the bins if the local signal does not match the received signal;

selecting a next bin according to the weightings; and

repeating the comparing using subsequent next bins at least until the local signal, having a phase corresponding to the subsequent next bin, matches the received signal.

2. The method of claim 1 wherein selecting the next bin is based on the transmission medium.

3. The method of claim 1 wherein selecting the next bin is based on selecting randomly and uniformly from the range of bins excluding the previously selected bin.

4. The method of claim 1 wherein selecting the next bin is based on a posteriori probability.

5. The method of claim 4 further comprising updating the weightings according to the posteriori probability.

6. The method of claim 1 further comprising updating the weightings except when a previous bin is assigned a weighting of zero.

7. The method of claim 1 wherein selecting the next bin is based on a fixed serial search.

8. The method of claim 1 further comprising performing at least one preliminary comparison between the local signal and the received signal.

9. The method of claim 1 wherein the next bin is a cluster of bins and performing the comparing, reporting, assigning, and selecting during a same selection period.

10. An apparatus for searching for a signal comprising:

a selecting unit configured to select a first bin within a range of bins, each bin corresponding to a phase of a transmitted signal;

a comparing unit configured to compare a local signal, having a phase corresponding to the first bin, with a received signal, the received signal being received via a transmission medium;

a reporting unit configured to report whether the local signal matches the received signal;

an assigning unit configured to assign weightings to the bins if the local signal and the received signal do not match;

the selecting unit further configured to select a next bin according to the weightings; and

the comparing unit further configured to compare subsequent bins at least until the local signal, having a phase corresponding to the next bin, matches the received signal.

11. The apparatus of claim 10 wherein the selecting unit is further configured to select the next bin based on the transmission medium.

12. The apparatus of claim 10 wherein the selecting unit is further configured to select the next bin based on a posteriori probability.

13. The apparatus of claim 12 wherein the assigning unit is further configured to update the weightings according to the posteriori probability.

14. A method for searching for a signal comprising:

selecting a first bin within a range of bins, each bin corresponding to a phase of a transmitted signal;

comparing a local signal, having a phase corresponding to the first bin, with a received signal, the received signal being received via a transmission medium;

reporting whether the local signal matches the received signal;

selecting a next bin based on the transmission medium by determining a characteristic of the received signal; and

repeating the comparing using subsequent bins until the local signal, having a phase corresponding to the next bin, matches the received signal.

15. The method of claim 14 wherein the characteristic of the received signal is signal strength.

16. The method of claim 14 further comprising:

assigning weightings to the bins if a match is not detected; and

using the weightings in a next bin selection.

17. The method of claim 14 wherein selecting the next bin is based on selecting randomly and uniformly from the range of bins excluding the previously selected bin.

18. The method of claim 14 wherein selecting the next bin is based on a posteriori probability.

19. The method of claim 14 wherein selecting the next bin is based on a fixed serial search.

20. The method of claim 14 further comprising:

performing at least one preliminary comparison between the local signal and the received signal.

21. The method of claim 14 wherein the next bin is a cluster of bins and performing the comparing, reporting, assigning, and selecting during a same selection period.

22. An apparatus for searching for a signal comprising:

a selecting unit configured to select a first bin within a range of bins, each bin corresponding to a phase of a transmitted signal;

a comparing unit configured to compare a local signal, having a phase corresponding to the first bin, with a received signal, the received signal being received via a transmission medium;

a reporting unit configured to report whether the local signal matches the received signal;

the selecting unit further configured to select a next bin based on the transmission medium by determining a characteristic of the received signal; and

the comparing unit further configured to compare subsequent bins at least until the local signal, having a phase corresponding to the next bin, matches the received signal.

23. The apparatus of claim 22 wherein the characteristic of the received signal is signal strength.

24. The apparatus of claim 22 further comprising an assigning unit configured to assign weightings to the bins if the local signal and the received signal do not match.

25. The apparatus of claim 22 wherein the selecting unit is further configured to select the next bin based on a posteriori probability.