Method and apparatus for determining boundaries of information elements

• US 8,031,816 B2
• Filed: 07/17/2006
• Issued: 10/04/2011
• Est. Priority Date: 07/17/2006
• Status: Expired due to Fees

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Chen, Kun-tso
• Primary Examiner(s): Payne; David C.
• Assistant Examiner(s): KASSA, ZEWDU A
• Application Number:
  US11/457,989
• Publication Number:
  US 20080013604A1
• Time in Patent Office: 1,905 Days
• Field of Search: 375/343, 375/340, 375/316, 375/354, 370/320
• US Class Current: 375/343
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073

Abstract

A method for determining boundaries of information elements for a PRN code modulated signal is provided. The method of the present invention measures a symbol phase of the received signal and correlation values of different durations to determine the information element boundary. By the method of the present invention, the determination of the information element boundary can be more effective especially in the common dump receiver architecture, wherein a reference wave used in the correlation measurement of the receiver cannot match the received waveform exactly.

Claims

1. A method for determining information element boundary of a signal, the signal having a plurality of information elements, each information element consisting of a group of codes, said method comprising steps of:

obtaining a symbol phase of the signal;

calculating energies of the signal over a predetermined duration for a plurality of a first group of time units and dumping the energies into a first energy value;

calculating energies of the signal over the predetermined duration for the plurality of a second group of time units and dumping the energies into a second energy value;

comparing the first and second energy values; and

determining which of the first and second groups of time units the information element boundary is in according to the comparing result of the first and second energy values and the symbol phase.

2. The method of claim 1, wherein the predetermined duration is a period of the information element.

3. The method of claim 2, wherein the information element boundary is determined according to the comparing result of the first and second energy values and whether the symbol phase is greater than a predetermined value.

4. The method of claim 3, wherein the energies of the signal for the plurality of first and second groups of time units are respectively dumped into the first and second energy values based on a first function of the symbol phase when the symbol phase is not greater than the predetermined value, while based on a second function of the symbol phase when the symbol phase is greater than the predetermined value.

5. The method of claim 4, wherein the second function is an inverse of the first function.

6. The method of claim 3, wherein the predetermined value is the middle value of one time unit.

7. The method of claim 1, wherein the predetermined duration is a period of a code.

8. The method of claim 1, wherein the first group of time units are odd time units and the second group of time units are even time units.

9. The method of claim 1, wherein one time unit is one code period.

10. The method of claim 1, further comprising a step of determining a beginning time point of correlation according to the symbol phase after determining which of the first and second groups of time units the information element boundary is in.

11. A method for determining information element boundary of a signal, the signal having a plurality of information elements, each information element consisting of a group of codes, said method comprising steps of:

obtaining a symbol phase of the signal;

calculating energies of the signal over a first duration for a plurality of a first group of time units and dumping the energies into a first energy value;

calculating energies of the signal over the first duration for the plurality of a second group of time units and dumping the energies into a second energy value;

calculating energies of the signal over a second duration for the plurality of the first group of time units and dumping the energies into a third energy value;

calculating energies of the signal over the second duration for the plurality of the second group of time units and dumping the energies into a fourth energy value; and

determining which of the first and second groups of time units the information element boundary is in according to the energy values and the symbol phase.

12. The method of claim 11, wherein the first duration is a period of one information element.

13. The method of claim 11, wherein the second duration is a period of one code.

14. The method of claim 11, further comprising selecting to compare the first and second energy values or to compare the third and fourth energy values to determine the information element boundary according to the symbol phase.

15. The method of claim 14, wherein the comparing step is selected depending on whether the symbol phase is within a predetermined range.

16. The method of claim 11, further comprising comparing the first and second energy values and comparing the third and fourth energy values, the information element boundary is determined according to the comparing results and the symbol phase.

17. The method of claim 16, wherein the information element boundary is determined according the comparing results and whether the symbol phase is greater than a predetermined value.

18. The method of claim 17, wherein the predetermined value is the middle value of one time unit.

19. The method of claim 11, wherein the first duration is one information element period.

20. The method of claim 11, wherein the second duration is one code period.

21. The method of claim 11, wherein the first group of time units are odd time units and the second group of time units are even time units.

22. The method of claim 11, wherein one time unit is one code period.

23. The method of claim 12, further comprising a step of determining a beginning time point of correlation according to the symbol phase after determining which of the first and second groups of time units the information element boundary is in.

24. A synchronizer for determining information element boundary of a signal, the signal having a plurality of information elements, each information element consisting of a group of codes, said synchronizer comprising:

a first register accumulating correlations of the signal over a first duration for a plurality of a first group of time units as a first energy value;

a second register accumulating correlations of the signal over the first duration for the plurality of a second group of time units as a second energy value; and

a detector comparing the first and second energy values to determine which of the first and second groups of time units the information element boundary is in according to the comparing result of the first and second energy values and a symbol phase of the signal.

25. The synchronizer of claim 24, wherein the first duration is a period of the information element.

26. The synchronizer of claim 24, further comprising a symbol phase checking block checking if the symbol phase is greater than a predetermined value, the detector determines the information element boundary according to the comparing result of the first and second energy values and checking result for the symbol phase.

27. The synchronizer of claim 26, further comprising a negation block for inverting the correlation when symbol phase checking block determines that the symbol phase is greater than the predetermined value.

28. The synchronizer of claim 26, wherein the predetermined value is the middle value of one time unit.

29. The synchronizer of claim 24, wherein the first duration is a period of the code.

30. The synchronizer of claim 24, wherein the first group of time units are odd time units and the second group of time units are even time units.

31. The synchronizer of claim 24, wherein one time unit is one code period.

32. The synchronizer of claim 24, further comprising:

a third register accumulating correlations of the signal over a second duration for a plurality of the first group of time units as a third energy value; and

a fourth register accumulating correlations of the signal over the second duration for the plurality of the second group of time units as a fourth energy value,

the detector determine which of the first and second groups of time units the information element boundary is in according to the first, second, third and fourth energy values.

33. The synchronizer of claim 32, wherein the detector selects to compare the first and second energy values or compare the third and fourth energy values according to the symbol phase, and determines the information element boundary according to the comparing result.

34. The synchronizer of claim 32, wherein the detector combines comparison of the first and second energy values and comparison of the third and fourth energy values and determines the information element boundary according to the combined comparison result.