Symmetric pilot processing for robust timing offset and frequency offset estimation in ISDB-T and ISDB-TSB receivers

1. A method of computing timing and frequency offset in sub-carriers in an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) receiver system, said method comprising:

storing said sub-carriers in a storage device;

using a processor for dividing said sub-carriers into two sub-sets, wherein said sub-sets comprise an equal number of sub-carriers;

removing bad sub-carriers from a first sub-set of said sub-sets;

removing sub-carriers from a second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets;

computing a phase difference on each sub-carrier from each sub-set responsive to the removing steps;

computing mean phase differences of each of said sub-sets responsive to the computing step; and

computing a timing offset and a frequency offset in said sub-carriers using the computed mean differences.

2. The method of claim 1 , wherein said frequency offset in said sub-carriers is computed by summing said mean phase differences of said sub-sets.

3. The method of claim 1 , wherein said timing offset in said sub-carriers is computed by calculating the difference of said mean phase differences of said sub-sets.

4. The method of claim 1 , wherein a bad sub-carrier occurs when a magnitude of a received signal in said sub-carrier is smaller than a predetermined threshold level.

5. The method of claim 1 , wherein said sub-carriers from said second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets are bad sub-carriers.

6. The method of claim 1 , wherein said sub-carriers from said second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets are good sub-carriers.

7. The method of claim 6 , wherein a good sub-carrier occurs when a magnitude of a received signal in said sub-carrier is equal to or larger than a predetermined threshold level.

8. A non-transitory program storage device readable by computer, tangibly embodying a program of instructions executable by said computer to perform a method of computing timing and frequency offset in sub-carriers in an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) receiver system, said method comprising:

using a processor for dividing said sub-carriers into two sub-sets, wherein said sub-sets comprise an equal number of sub-carriers;

removing bad sub-carriers from a first sub-set of said sub-sets;

removing sub-carriers from a second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets;

computing a phase difference on each sub-carrier from each sub-set responsive to the removing steps;

computing mean phase differences of each of said sub-sets responsive to the computing step; and

computing a timing offset and a frequency offset in said sub-carriers using the computed mean differences.

9. The program storage device of claim 1 , wherein said frequency offset in said sub-carriers is computed by summing said mean phase differences of said sub-sets.

10. The program storage device of claim 1 , wherein said timing offset in said sub-carriers is computed by calculating the difference of said mean phase differences of said sub-sets.

11. The program storage device of claim 1 , wherein a bad sub-carrier occurs when a magnitude of a received signal in said sub-carrier is smaller than a predetermined threshold level.

12. The program storage device of claim 1 , wherein said sub-carriers from said second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets are bad sub-carriers.

13. The program storage device of claim 1 , wherein said sub-carriers from said second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets are good sub-carriers.

14. The program storage device of claim 13 , wherein a good sub-carrier occurs when a magnitude of a received signal in said sub-carrier is equal to or larger than a predetermined threshold level.

15. An apparatus for computing timing and frequency offset in sub-carriers in an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) receiver system, said apparatus comprising:

a storage device for storing said sub-carriers;

a processor for dividing said sub-carriers into two sub-sets, wherein said sub-sets comprise an equal number of sub-carriers;

digital logic means for removing bad sub-carriers from a first sub-set of said sub-sets;

digital logic means for removing sub-carriers from a second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets;

means for computing a phase difference on each sub-carrier from each sub-set;

means for computing mean phase differences of each of said sub-sets; and

means for computing a timing offset and a frequency offset in said sub-carriers using the computed mean differences.

16. The apparatus of claim 15 , wherein said frequency offset in said sub-carriers is computed by summing said mean phase differences of said sub-sets.

17. The apparatus of claim 15 , wherein said timing offset in said sub-carriers is computed by calculating the difference of said mean phase differences of said sub-sets.

18. The apparatus of claim 15 , wherein a bad sub-carrier occurs when a magnitude of a received signal in said sub-carrier is smaller than a predetermined threshold level.

19. The apparatus of claim 15 , wherein said sub-carriers from said second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets are bad sub-carriers.

20. The apparatus of claim 15 , wherein said sub-carriers from said second sub-set of said sub-sets that correspond to said bad sub-carriers from said first sub-set of said subsets are good sub-carriers, wherein a good sub-carrier occurs when a magnitude of a received signal in said sub-carrier is equal to or larger than a predetermined threshold level.