COHERENT INITIAL ACQUISITION

• US 20080220723A1
• Filed: 09/24/2007
• Published: 09/11/2008
• Est. Priority Date: 03/05/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Krishnamoorthi, Raghuraman, Ling, Fuyun, Huang, Yuheng, Tian, Tao
• Granted Patent: US 8,325,856 B2
• Time in Patent Office: Days
• US Class Current: 455/59
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

An acquisition module includes a coherent correlator configured to receive a transmission having a pilot signal and correlate the received transmission with a local copy of the pilot signal to produce a first output, a delayed correlator configured to delay the first output and correlate the first output with the delayed first output to produce a second output, and a detector configured to detect the pilot signal in the transmission based on the second output.

Claims

1. An acquisition module, comprising:

a coherent correlator configured to receive a transmission having a pilot signal and correlate the received transmission with a local copy of the pilot signal to produce a first output;

a delayed correlator configured to delay the first output and correlate the first output with the delayed first output to produce a second output; and

a detector configured to detect the pilot signal in the transmission based on the second output.

2. The acquisition module of claim 1 further comprising a threshold filter configured to filter the second output and providing the filtered second output to the detector for pilot signal detection.

3. The acquisition module of claim 1 wherein the detector is further configured to generate timing information for the received transmission based on the second output.

4. The acquisition module of claim 1 wherein the transmission includes a super frame containing the pilot signal, and wherein the detector is further configured to derive the timing of the super frame based on the second output.

5. The acquisition module of claim 1 wherein the detector is further configured derive a frequency offset for the transmission based on the second output.

6. The acquisition module of claim 1 wherein the detector comprises a state machine.

7. The acquisition module of claim 6 wherein the pilot signal comprises a periodic sequence, and wherein the delayed correlator is further configured to produce a peak for each of the periods in the pilot signal, and wherein the state machine is further configured to detect the pilot signal when one or more of the peaks are missing due to noise or interference.

8. The acquisition module of claim 6 wherein the pilot signal comprises a periodic sequence, and wherein the delayed correlator is further configured to produce a peak for each of the periods in the pilot signal, and wherein the state machine is further configured to detect one or more peaks due to noise and interference and not declare a pilot signal in response thereto.

9. The acquisition module of claim 1 wherein the coherent correlator comprises a frequency domain correlator and the delayed correlator comprises a time domain correlator.

10. An acquisition module, comprising:

means for receiving a transmission having a pilot signal;

means for correlating the received transmission with a local copy of the pilot signal to produce a first output;

means for delaying the first output;

means for correlating the first output with the delayed first output to produce a second output; and

means for detecting the pilot signal in the transmission based on the second output.

11. The acquisition module of claim 10 further comprising means for threshold filtering the second output and providing the filtered output to the means for detecting the pilot signal for pilot signal detection.

12. The acquisition module of claim 10 wherein the means for detecting the pilot signal comprises means for generating timing information for the received transmission based on the second output.

13. The acquisition module of claim 10 wherein the transmission includes a super frame containing the pilot signal, and wherein the means for detecting the pilot signal comprises means for deriving the timing of the super frame based on the second output.

14. The acquisition module of claim 10 wherein the means for detecting the pilot signal comprises means for deriving a frequency offset for the transmission based on the second output.

15. The acquisition module of claim 14 wherein the pilot signal comprises a periodic sequence, and wherein the means for correlating the first output with the delayed first output comprises means for producing a peak for each of the periods in the pilot signal, and wherein the means for detecting the pilot is further configured to detect the presence of the pilot signal when one or more of the peaks are missing due to noise or interference.

16. The acquisition module of claim 10 wherein the pilot signal comprises a periodic sequence, and wherein the means for correlating the first output with the delayed first output comprises means for producing a peak for each of the periods in the pilot signal, and wherein the means for detecting the pilot signal comprises means for detecting one or more peaks due to noise and interference and not declaring a pilot signal in response thereto.

17. The acquisition module of claim 10 wherein the means for correlating the received transmission with a local copy of the pilot signal comprises a frequency domain coherent correlator and the means for correlating the first output with the delayed first output comprises a time domain delayed correlator.

18. A method of telecommunications, comprising:

receiving a transmission having a pilot signal;

correlating the received transmission with a local copy of the pilot signal to produce a first output;

delaying the first output;

correlating the first output with the delayed first output to produce a second output; and

detecting the pilot signal in the transmission based on the second output.

19. The method of claim 18 further comprising threshold filtering the second output, and wherein the detection of the pilot signal is derived from the filtered second output.

20. The method of claim 18 wherein the detection of the pilot signal comprises generating timing information for the received transmission based on the second output.

21. The method of claim 18 wherein the transmission includes a super frame containing the pilot signal, and wherein the detection of the pilot signal comprises deriving the timing of the super frame based on the second output.

22. The method of claim 18 wherein the detection of the pilot signal comprises deriving a frequency offset for the transmission based on the second output.

23. The method of claim 18 wherein the pilot signal comprises a periodic sequence, and wherein the correlation of the first output with the delayed first output produces a peak for each of the periods in the pilot signal, and wherein the pilot signal is detected when one or more of the peaks are missing due to noise or interference.

24. The method of claim 18 wherein the pilot signal comprises a periodic sequence, and wherein the correlation of the first output with the delayed first output produces a peak for each of the periods in the pilot signal, the method further comprising not declaring a pilot signal in response to one or more peaks due to noise and interference.

25. A machine-readable medium comprising instructions executable by a processing system in a mobile service provider, the instructions comprising code for:

receiving a transmission having a pilot signal;

correlating the received transmission with a local copy of the pilot signal to produce a first output;

delaying the first output;

correlating the first output with the delayed first output to produce a second output; and

detecting the pilot signal in the transmission based on the second output.