Claims
- 1. A method for processing a signal in a communication system, said method comprising the steps of:
receiving said signal; correlating said signal with itself to identify a peak in each frame; and aligning said peak with a desired position within said frame, said desired position being removed from a frame boundary.
- 2. The method according to claim 1, wherein said desired position is a central position in said frame.
- 3. The method according to claim 1, further comprising the step of establishing a plurality of windows in each frame during an acquisition mode and determining a peak in each of said windows.
- 4. The method according to claim 3, further comprising the step of selecting a timing estimate associated with a peak in one of said windows for timing purposes if said timing estimate satisfies at least one predefined condition.
- 5. The method according to claim 4, wherein said at least one predefined condition ensures that said timing estimate does not vary by more than a guard interval for a predefined number of frames.
- 6. The method according to claim 5, further comprising the step of declaring that timing has been acquired when said at least one predefined criteria is satisfied.
- 7. The method according to claim 1, further comprising the step of declaring that timing has been lost during a tracking mode when said peak varies from said desired position by more than a guard interval in said signal for more than a predefined number of frames.
- 8. The method according to claim 1, wherein said correlating step determines the maximum likelihood (ML) metric of said signal.
- 9. The method according to claim 1, wherein said correlating step is performed at a lag of the useful symbol duration.
- 10. The method according to claim 1, wherein said signal is an OFDM signal.
- 11. The method according to claim 1, wherein said signal is a DMT signal.
- 12. A method for processing a signal in a communication system, said method comprising the steps of:
receiving said signal; identifying a peak in each frame; and aligning said peak with a desired position within said frame, said desired position being removed from a frame boundary.
- 13. The method according to claim 12, wherein said desired position is a central position in said frame.
- 14. The method according to claim 12, further comprising the step of establishing a plurality of windows in each frame during an acquisition mode and determining a peak in each of said windows.
- 15. The method according to claim 14, further comprising the step of selecting a timing estimate associated with a peak in one of said windows for timing purposes if said timing estimate satisfies at least one predefined condition.
- 16. The method according to claim 15, wherein said at least one predefined condition ensures that said timing estimate does not vary by more than a guard interval for a predefined number of frames.
- 17. The method according to claim 16, further comprising the step of declaring that timing has been acquired when said at least one predefined criteria is satisfied.
- 18. The method according to claim 12, further comprising the step of declaring that timing has been lost during a tracking mode when said peak varies from said desired position by more than a guard interval in said signal for more than a predefined number of frames.
- 19. The method according to claim 12, wherein said correlating step determines the maximum likelihood (ML) metric of said signal.
- 20. The method according to claim 12, wherein said identifying step further comprises the step of correlating said signal with itself at a lag of the useful symbol duration to identify a peak in each frame step.
- 21. A receiver for receiving a signal, comprising:
a maximum index locator to identify a peak in each frame; and an alignment block for aligning said peak with a desired position within said frame, said desired position being removed from a frame boundary.
- 22. The receiver according to claim 21, wherein said desired position is a central position in said frame.
- 23. The receiver according to claim 21, wherein a peak is identified in a plurality of windows in each frame during an acquisition mode.
- 24. The receiver according to claim 23, wherein a timing estimate associated with a peak in one of said windows is selected for timing purposes if said timing estimate satisfies at least one predefined condition.
- 25. The receiver according to claim 24, wherein said at least one predefined condition ensures that said timing estimate does not vary by more than a guard interval for a predefined number of frames.
- 26. The receiver according to claim 25, wherein timing is acquired when said at least one predefined criteria is satisfied.
- 27. The receiver according to claim 21, wherein timing is lost during a tracking mode when said peak varies from said desired position by more than a guard interval in said signal for more than a predefined number of frames.
- 28. The receiver according to claim 21, wherein said maximum index locator determines the maximum likelihood (ML) metric of said signal.
- 29. The receiver according to claim 21, wherein said maximum index locator operates at a lag of the useful symbol duration.
- 30. The receiver according to claim 21, wherein said signal is an OFDM signal.
- 31. The receiver according to claim 21, wherein said signal is a DMT signal.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present invention is related to U.S. patent application Ser. No. 09/398,502, filed Sep. 17, 1999, entitled “Method and Apparatus for Performing Differential Modulation Over Frequency in an Orthogonal Frequency Division Multiplexing (OFDM) Communication System,” (Attorney Docket Number Riazi 3-11-3), assigned to the assignee of the present invention and incorporated by reference herein.