Coherent initial acquisition

• US 8,325,856 B2
• Filed: 09/24/2007
• Issued: 12/04/2012
• Est. Priority Date: 03/05/2007
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Krishnamoorthi, Raghuraman, Tian, Tao, Ling, Fuyun, Huang, Yuheng
• Primary Examiner(s): PATEL, DHAVAL V
• Application Number:
  US11/860,505
• Publication Number:
  US 20080220723A1
• Time in Patent Office: 1,898 Days
• Field of Search: 375/343, 375/135, 375/136, 375/146, 375/147, 375/149, 375/150, 375/236, 375/340, 375/344, 375/371, 375/375, 455/59, 370/320, 370/335, 370/342, 370/441, 370/479, 370/515, 708/300, 708/422, 708/813, 708/819
• US Class Current: 375/343
• 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 in hardware device 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 state machine configured to accumulate a first number of high energy peaks in the second output during a sampling period and detect the pilot signal by comparing a magnitude of the accumulated high energy peaks with a magnitude threshold and the first number with a hit threshold and a miss threshold,

wherein the first number corresponds to a number of times the high energy peaks exceed the magnitude threshold, and

wherein the state machine is further configured to;

declare that the pilot signal was detected when the first number exceeds the hit threshold,

continue accumulating high energy peaks if the first number is between the miss threshold and the hit threshold, and

restart pilot signal acquisition when the first number is below the miss threshold.

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

3. The acquisition module of claim 1 wherein the state machine 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 state machine 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 state machine is further configured to derive a frequency offset for the transmission based on the second output.

6. The acquisition module of claim 1 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.

7. The acquisition module of claim 1 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.

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

9. 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 accumulating a first number of high energy peaks in the second output during a sampling period;

means for detecting the pilot signal by comparing a magnitude of the accumulated high energy peaks with a first magnitude threshold and the first number with a hit threshold and a miss threshold;

means for declaring that the pilot signal was detected when the first number exceeds the hit threshold;

means for continuing accumulating high energy peaks if the first number is between the miss threshold and the hit threshold; and

means for restarting pilot signal acquisition when the first number is below the miss threshold wherein the first number of high energy peaks corresponds to a number of times the high energy peaks exceed the first magnitude threshold.

10. The acquisition module of claim 9 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.

11. The acquisition module of claim 9 wherein the means for detecting the pilot signal comprises means for generating timing information for the received transmission based on the second output.

12. The acquisition module of claim 9 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.

13. The acquisition module of claim 9 wherein the means for detecting the pilot signal comprises means for deriving a frequency offset for the transmission based on the second output.

14. The acquisition module of claim 13 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.

15. The acquisition module of claim 9 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.

16. The acquisition module of claim 9 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.

17. 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;

accumulating a first number of high energy peaks in the second output during a sampling period;

detecting the pilot signal by comparing a magnitude of the accumulated high energy peaks with a first magnitude threshold and the first number with a hit threshold and a miss threshold;

declaring that the pilot signal was detected when the first number exceeds the hit threshold;

continuing accumulating high energy peaks if the first number is between the miss threshold and the hit threshold; and

restarting pilot signal acquisition when the first number is below the miss threshold, wherein the first number corresponds to a number of times the high energy peaks exceed the first magnitude threshold.

18. The method of claim 17 further comprising threshold filtering the second output, and wherein the detection of the pilot signal is derived from the filtered second output.

19. The method of claim 17 wherein the detection of the pilot signal comprises generating timing information for the received transmission based on the second output.

20. The method of claim 17 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.

21. The method of claim 17 wherein the detection of the pilot signal comprises deriving a frequency offset for the transmission based on the second output.

22. The method of claim 17 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.

23. The method of claim 17 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. The method of claim 17 wherein the correlation of the received transmission with a local copy of the pilot signal comprises a frequency domain coherent correlation and the correlation of the first output with the delayed first output comprises a time domain delayed correlation.

24. A non-transitory 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;

accumulating a first number of high energy peaks in the second output during a sampling period;

detecting the pilot signal by comparing a magnitude of the accumulated high energy peaks with a first magnitude threshold and the first number with a hit threshold and a miss threshold;

declaring that the pilot signal was detected when the first number exceeds the hit threshold;

continuing accumulating high energy peaks if the first number is between the miss threshold and the hit threshold; and

restarting pilot signal acquisition when the first number is below the miss threshold, wherein the first number corresponds to a number of times the high energy peaks exceed the first magnitude threshold.

26. The non-transitory machine-readable medium of claim 24 further comprising code for threshold filtering the second output, and wherein the code for detecting the pilot signal comprises code for deriving detection from the filtered second output.

27. The non-transitory machine-readable medium of claim 24 wherein the code for the detecting the pilot signal comprises code for generating timing information for the received transmission based on the second output.

28. The non-transitory machine-readable medium of claim 24 wherein the code for receiving the transmission having a pilot signal includes code for receiving a transmission having a super frame containing the pilot signal, and wherein the code for detecting the pilot signal comprises code for deriving the timing of the super frame based on the second output.

29. The non-transitory machine-readable medium of claim 24 wherein the code for the detecting the pilot signal comprises code for deriving a frequency offset for the transmission based on the second output.

30. The non-transitory machine-readable medium of claim 24 wherein the pilot signal comprises a periodic sequence, and wherein the code for correlating the first output with the delayed first output comprises code for producing a peak for each of the periods in the pilot signal, and wherein the code for detecting the pilot signal comprises code for detecting when one or more of the peaks are missing due to noise or interference.

31. The non-transitory machine-readable medium of claim 24 wherein the pilot signal comprises a periodic sequence, and wherein the code for correlating the first output with the delayed first output comprises code for producing a peak for each of the periods in the pilot signal, and further comprising code for not declaring a pilot signal in response to one or more peaks due to noise and interference.

32. The non-transitory machine-readable medium of claim 24 wherein the code for correlating the received transmission with a local copy of the pilot signal comprises code for a frequency domain coherent correlation and the code for correlating the first output with the delayed first output comprises code for a time domain delayed correlation.