Method and apparatus for generating a preamble for use in cable transmission systems

1. A method for generating a preamble for use in a cable transmission system, the method comprising the steps of:

selecting a complementary sequence;

receiving signaling bits representing system information and encoding said signaling bits with an error correction code to produce encoded signaling bits;

mapping the complementary sequence and encoded signaling bits into modulation symbols;

using the modulation symbols to modulate allocated even carriers only of the frequency domain representation of an OFDM symbol contained in a frame of the cable transmission signal, wherein said cable transmission signal is comprised of a plurality of frames, said frame is comprised of at least one OFDM symbol, said OFDM symbol forms the preamble in each frame and the modulation symbols from the complementary sequence are assigned to the beginning carriers of the OFDM symbol as a header; and

transforming the preamble to its time domain representation for transmission.

2. The method according to claim 1 , further comprising

setting a length of the complementary sequence according to cable carrier conditions.

3. The method according to claim 1 , further comprising reserving at least one of the allocated even carriers for pilot carriers.

4. The method according to claim 3 , further comprising using the pilot carriers to measure carrier conditions.

5. The method according to claim 3 , further comprising re-using channel gain coefficients on the pilot carriers in following OFDM symbols.

6. The method according to claim 1 , wherein said mapping further comprises using orthogonal codes to convey the signaling bits of system information.

7. The method according to claim 6 , further comprising selecting the orthogonal codes in response to a number of required system information bits and channel conditions.

8. The method according to claim 6 , wherein the orthogonal codes comprise Walsh codes.

9. The method according to claim 1 , further comprising the step of adding a cyclic prefix to complete the generation of the preamble.

10. The method according to claim 1 , further comprising:

bonding two or more channels; and

ensuring the generated preamble repeated in frequency fills a complete spectrum of the bonded channels.

11. The method according to claim 10 , further comprising:

restricting a number of carriers used by said preamble to be less than or equal to a number of carriers used in an OFDM symbol.

12. The method according to claim 1 , wherein said mapping further comprises using QAM modulation symbols to convey the signaling bits of system information.

13. The method according to claim 1 , wherein said error correction codes comprises a Reed-Muller codes.

14. An apparatus for generating a preamble for use in a cable transmission system comprising:

a processor for inserting a complementary sequence as a header in beginning carriers, encoding the signaling bits of the system with an error correction code and mapping the complementary sequence and encoded signaling bits into modulation symbols to form the preamble; and

a modulator configured to allocate even carriers only and enable the transmission of the preamble on the allocated even carriers.

15. The apparatus of claim 14 , wherein the processor further enables the bonding of two or more channels in the cable transmission system and ensures that the generated preamble repeated in frequency fills a complete spectrum of the bonded channels.

16. The apparatus of claim 15 , wherein carrier conditions are measured using the pilot carrier.

17. The apparatus of claim 14 , wherein the processor further restricts a number of carriers used by the preamble to be less than or equal to a number of carriers use in an OFDM symbol.

18. The apparatus of claim 14 , wherein the processor reserves at least one of the allocated even carriers for use with a pilot carrier.

19. The apparatus of claim 14 , wherein orthogonal codes are used to convey the signaling bits of system information.

20. The apparatus of claim 14 , wherein the error correction codes comprises a Reed-Muller codes.

21. A method for receiving and processing a preamble for use in a cable transmission medium, the method comprising the steps of:

transforming the preamble from the time domain to the frequency domain;

retrieving modulation symbols from the allocated even carriers only of the frequency domain representation of the preamble;

retrieving a complementary sequence and encoded signaling bits from said modulation symbols wherein the complementary sequence is the header associated with the modulation symbols of the beginning carriers of the preamble; and

decoding the encoded signaling bits with an error correction decoder to retrieve the signaling bits representing system information.

22. The method according to claim 21 , wherein at least one of the allocated even carriers is used for pilot carriers.

23. The method according to claim 22 , wherein the pilot carriers are used to measure carrier conditions.

24. The method according to claim 22 , wherein channel gain coefficients are used on the pilot carriers in following OFDM symbols.

25. The method according to claim 21 , wherein said mapping further comprises using QAM modulation symbols to convey the signaling bits of system information.

26. An apparatus for receiving and processing a preamble for use in a cable transmission system comprising:

a demodulator configured to process even carriers only and enable the reception of the preamble on the allocated even carriers; and

a processor for retrieving the modulation symbols that form the preamble from said even carriers, retrieving a complementary sequence as a header in beginning carriers from said modulation symbols, retrieving encoded signaling bits from said modulation symbols and decoding the encoded signaling bits with an error correction decoder to retrieve signaling bits representing system information.

27. The apparatus of claim 26 , wherein the processor receives at least one of the allocated even carriers used with a pilot carrier.

28. The apparatus of claim 26 , wherein orthogonal codes are processed that have been used to convey the signaling bits of system information.