Scattered pilot correlation in DVB-H systems

1. A method for correlating scattered pilot locations in a sequence of orthogonal-frequency-division-multiplexing (OFDM) symbols transmitted by a transmitter and received by a receiver in a multi-carrier transmission system, said OFDM symbols comprising continuous pilot symbols and scattered pilot symbols, said method comprising:

mapping pilot locations comprising pilot symbols having predetermined known values, wherein said pilot symbols are positioned among data subcarriers in time and frequency dimensions consisting of received pilot symbols and having a predetermined position pattern in said time and frequency dimensions, wherein said predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of said pilot symbols;

estimating a Doppler spread in a frequency spectrum between said transmitter and said receiver in said multi-carrier transmission system;

estimating a channel length of a set of channel paths received at said receiver;

providing a predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols; and

said receiver automatically selecting said predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols based only on the estimating processes, wherein the selecting process comprises:

grouping a range of all pilot symbols located in a single subcarrier corresponding to a dynamic time dimension and a single frequency dimension, wherein said range comprises all pilot symbols located between and including a first received scattered pilot symbol and a last received scattered pilot symbol received in a single subcarrier;

buffering said range of all pilot symbols located in a single subcarrier;

disregarding a change in subcarrier values across said range of all pilot symbols located in a single subcarrier;

creating a graphical pilot correlation sequence corresponding to the buffered range of all pilot symbols located in a single subcarrier;

locating peaks in said pilot correlation sequence; and

identifying said peaks as scattered pilot symbol locations.

2. The method of claim 1 , wherein said multi-carrier transmission system comprises a Digital Video Broadcasting-Handheld (DVB-H) system.

3. The method of claim 1 , wherein said range of all pilot symbols located in a single subcarrier equals four pilot symbols.

4. The method of claim 1 , wherein said OFDM symbols are received in a slow fading channel.

5. The method of claim 1 , wherein said buffering of said range of all pilot symbols located in a single subcarrier comprises buffering four received OFDM symbols.

6. A method comprising:

providing orthogonal-frequency-division-multiplexing (OFDM) symbols comprising continuous pilot symbols and scattered pilot symbols;

mapping pilot locations comprising pilot symbols having predetermined known values, wherein said pilot symbols are positioned among data subcarriers in time and frequency dimensions comprising received pilot symbols and having a predetermined position pattern in said time and frequency dimensions, wherein said predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of said pilot symbols;

estimating a Doppler spread in a frequency spectrum in a multi-carrier transmission system;

estimating a channel length of a set of channel paths;

providing a predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols; and

automatically selecting said predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols based only on the estimating processes, wherein the selecting process comprises:

grouping a range of all pilot symbols located in a single subcarrier corresponding to a dynamic time dimension and a single frequency dimension, wherein said range comprises all pilot symbols located between and including a first received scattered pilot symbol and a last received scattered pilot symbol received in a single subcarrier;

buffering said range of all pilot symbols located in a single subcarrier;

disregarding a change in subcarrier values across said range of all pilot symbols located in a single subcarrier;

creating a graphical pilot correlation sequence corresponding to the buffered range of all pilot symbols located in a single subcarrier;

locating peaks in said pilot correlation sequence; and

identifying said peaks as scattered pilot symbol locations.

7. The method of claim 6 , wherein said multi-carrier transmission system comprises a Digital Video Broadcasting-Handheld (DVB-H) system.

8. The method of claim 6 , wherein said range of all pilot symbols located in a single subcarrier equals four pilot symbols.

9. The method of claim 6 , wherein said OFDM symbols are received in a slow fading channel.

10. The method of claim 6 , wherein said buffering of said range of all pilot symbols located in a single subcarrier comprises buffering four received OFDM symbols.

11. A method for correlating scattered pilot locations in a sequence of orthogonal-frequency-division-multiplexing (OFDM) symbols received by a receiver in a multi-carrier transmission system, said OFDM symbols comprising continuous pilot symbols and scattered pilot symbols, said method comprising:

mapping pilot locations comprising pilot symbols having predetermined known values, wherein said pilot symbols are positioned among data subcarriers in time and frequency dimensions comprising received pilot symbols and having a predetermined position pattern in said time and frequency dimensions, wherein said predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of said pilot symbols;

estimating a Doppler spread in a frequency spectrum in said multi-carrier transmission system;

estimating a channel length of a set of channel paths received at said receiver;

providing a plurality of predetermined methods of correlating said scattered pilot locations in said sequence of OFDM symbols; and

automatically selecting one of said plurality of predetermined methods of correlating said scattered pilot locations in said sequence of OFDM symbols based only on the estimating processes, wherein the selecting process comprises:

grouping a range of all pilot symbols located in a single subcarrier corresponding to a dynamic time dimension and a single frequency dimension, wherein said range comprises all pilot symbols located between and including a first received scattered pilot symbol and a last received scattered pilot symbol received in a single subcarrier;

buffering said range of all pilot symbols located in a single subcarrier;

disregarding a change in subcarrier values across said range of all pilot symbols located in a single subcarrier;

creating a graphical pilot correlation sequence corresponding to the buffered range of all pilot symbols located in a single subcarrier;

locating peaks in said pilot correlation sequence; and

identifying said peaks as scattered pilot symbol locations.

12. The method of claim 11 , wherein said multi-carrier transmission system comprises a Digital Video Broadcasting-Handheld (DVB-H) system.

13. The method of claim 11 , wherein said range of all pilot symbols located in a single subcarrier equals four pilot symbols.

14. The method of claim 11 , wherein said OFDM symbols are received in a slow fading channel.

15. The method of claim 11 , wherein said buffering of said range of all pilot symbols located in a single subcarrier comprises buffering four received OFDM symbols.