System and method for scrambling the phase of the carriers in a multicarrier communications system

• US 7,292,627 B2
• Filed: 08/26/2005
• Issued: 11/06/2007
• Est. Priority Date: 11/09/1999
• Status: Expired due to Term

• Current Assignee: TQ Delta LLC (Techquity Capital Management, LLC)
• Original Assignee: Aware Incorporated (Crowley Holdings Preferred LLC)
• Inventors: Tzannes, Marcos C.
• Primary Examiner(s): Ghayour, Mohammed
• Assistant Examiner(s): WILLIAMS, LAWRENCE B
• Application Number:
  US11/211,535
• Publication Number:
  US 20060002454A1
• Time in Patent Office: 802 Days
• Field of Search: 375/220, 375/222, 375/219, 375/226, 375/260, 375/327, 375/362, 370/203, 370/342, 370/206
• US Class Current: 375/222
• CPC Class Codes: H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04L 25/03866 using scrambling
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2621 Reduction thereof using phase offsets between subcarriers
• CPC Class Codes: H04L 27/2627 Modulators

Abstract

A system and method that scrambles the phase characteristic of a carrier signal are described. The scrambling of the phase characteristic of each carrier signal includes associating a value with each carrier signal and computing a phase shift for each carrier signal based on the value associated with that carrier signal. The value is determined independently of any input bit value carried by that carrier signal. The phase shift computed for each carrier signal is combined with the phase characteristic of that carrier signal so as to substantially scramble the phase characteristic of the carrier signals. Bits of an input signal are modulated onto the carrier signals having the substantially scrambled phase characteristic to produce a transmission signal with a reduced PAR.

Claims

1. In a multicarrier modulation transceiver having a plurality of carrier signals for modulating an input bit stream, each carrier signal having a phase characteristic associated with the input bit stream, a method for scrambling the phase characteristics of the carrier signals comprising:

associating each carrier signal with a value determined independently of any input bit value carried by that carrier signal;

computing a phase shift for each carrier signal based on the value associated with that carrier signal; and

combining the phase shift computed for each carrier signal with the phase characteristic of that carrier signal so as to substantially scramble the phase characteristics of the plurality of carrier signals.

2. The method of claim 1 further comprising modulating bits of the input bit stream onto the carrier signals having the substantially scrambled phase characteristics to produce a transmission signal with a reduced peak-to-average power ratio (PAR).

3. The method of claim 1 further comprising independently deriving the value associated with each carrier signal at the first and a second transceiver.

4. The method of claim 1 further comprising transmitting the value associated with each carrier signal from the first transceiver to a second transceiver.

5. The method of claim 1 further comprising maintaining synchronization between the transceiver and a second transceiver using the value associated with each carrier signal.

6. The method of claim 1 wherein the value varies with each carrier signal.

7. The method of claim 1 wherein the value varies with each DMT symbol.

8. The method of claim 1 wherein the value is derived from a predetermined parameter.

9. The method of claim 8 wherein the predefined parameter is a carrier number.

10. The method of claim 8 wherein the predefined parameter is a symbol count.

11. The method of claim 8 wherein the predefined parameter is a hyperframe count.

12. The method of claim 8 wherein the predefined parameter is a superframe count.

13. The method of claim 1 further comprising scrambling the bits of the input bit stream.

14. The method of claim 1 further comprising transmitting a predetermined transmission signal when the amplitude of the transmission signal exceeds a certain level.

15. The method of claim 14 wherein the predetermined transmission signal comprises a predetermined pattern of bits.

16. The method of claim 14 wherein the predetermined transmission signal comprises a pilot tone.

17. The method of claim 16 wherein the pilot tone is used to maintain timing synchronization between the first transceiver and a second transceiver.

18. The method of claim 15 wherein each bit value in the predetermined pattern of bits is a zero value.

19. The method of claim 15 wherein the predetermined pattern of bits is a pseudo-random sequence pattern.

20. A multicarrier modulation transceiver that uses a transmission signal having a plurality of carrier signals for modulating an input bit stream, each carrier signal having a phase characteristic associated with the input bit stream, wherein the multicarrier modulation transceiver is capable of associating each carrier signal with a value determined independently of any input bit value carried by that carrier signal, computing a phase shift for each carrier signal based on the value associated with that carrier signal and combining the phase shift computed for each carrier signal with the phase characteristic of that carrier signal so as to substantially scramble the phase characteristics of the plurality of carrier signals.

21. The transceiver of claim 20 further comprising a modulator capable of modulating bits of the input bit stream onto the carrier signals having the substantially scrambled phase characteristics to produce a transmission signal with a reduced peak-to-average power ratio (PAR).

22. The transceiver of claim 20 wherein the transceiver communicates with a second transceiver, and the value associated with each carrier signal is independently derived at each transceiver.

23. The transceiver of claim 20 further comprising a transmitter that transmits the value associated with each carrier signal from the transceiver to a second transceiver.

24. The transceiver of claim 20 wherein synchronization is maintained between the transceiver and a second transceiver using the value associated with each carrier signal.

25. The transceiver of claim 20 wherein the value varies with each carrier signal.

26. The transceiver of claim 20 wherein the value varies with each DMT symbol.

27. The transceiver of claim 20 wherein the value is derived from a predetermined parameter.

28. The transceiver of claim 27 wherein the predefined parameter is a carrier number.

29. The transceiver of claim 27 wherein the predefined parameter is a symbol count.

30. The transceiver of claim 27 wherein the predefined parameter is a hyperframe count.

31. The transceiver of claim 27 wherein the predefined parameter is a superframe count.

32. The transceiver of claim 20 further comprising scrambling the bits of the input bit stream.

33. The transceiver of claim 20 further comprising transmitting a predetermined transmission signal when the amplitude of the transmission signal exceeds a certain level.

34. The transceiver of claim 33 wherein the predetermined transmission signal comprises a predetermined pattern of bits.

35. The transceiver of claim 33 wherein the predetermined transmission signal comprises a pilot tone.

36. The transceiver of claim 35 wherein the pilot tone is used to maintain timing synchronization between the first transceiver and a second transceiver.

37. The transceiver of claim 34 wherein each bit value in the predetermined pattern of bits is a zero value.

38. The transceiver of claim 34 wherein the predetermined pattern of bits is a pseudo-random sequence pattern.

39. The transceiver of claim 20 wherein the multicarrier modulation transceiver communicates with a second transceiver.