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

• US 7,769,104 B2
• Filed: 10/22/2008
• Issued: 08/03/2010
• Est. Priority Date: 11/09/1999
• Status: Expired due to Fees

• Current Assignee: TQ Delta LLC (Techquity Capital Management, LLC)
• Original Assignee: Aware Incorporated (Crowley Holdings Preferred LLC)
• Inventors: Tzannes, Marcos C.
• Primary Examiner(s): Bocure, Tesfaldet
• Assistant Examiner(s): Williams, Lawrence B
• Application Number:
  US12/255,713
• Publication Number:
  US 20090110105A1
• Time in Patent Office: 650 Days
• Field of Search: 375219-220, 375/222, 375/260, 375/267, 375/295, 375/362, 375/259, 375/261, 375/298, 370/57, 370/69.1, 370/281, 370/295, 370/330, 370/343, 370/436, 370/478, 370480-481, 370/206, 370/208, 455/73, 455/91, 455/108
• US Class Current: 375/298
• 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. A method to scramble the phase characteristics of carriers for multicarrier communications comprising:

assigning a carrier number to at least one carrier in a multicarrier symbol;

modulating, by a modulator, the at least one carrier with a QAM (Quadrature Amplitude Modulation) signal;

determining a phase shift for the at least one carrier based on the carrier number assigned to the at least one carrier wherein the phase shift is determined independently of the QAM signal; and

combining the phase shift with a phase characteristic of the at least one carrier so as to substantially scramble the phase characteristics of the carrier.

2. The method of claim 1, wherein the phase shift is determined using a function of the carrier number.

3. The method of claim 2, wherein the function of the carrier number comprises at least multiplying the carrier number by a predefined phase value.

4. A multicarrier transceiver that scrambles the phase characteristics of carriers comprising:

a transmitter capable of assigning a carrier number to at least one carrier in a multicarrier symbol;

a modulator capable of modulating the at least one carrier with a QAM (Quadrature Amplitude Modulation) signal; and

a phase scrambler capable of determining a phase shift for the at least one carrier based on the carrier number assigned to the at least one carrier, wherein the phase shift is determined independently of the QAM signal, and combining the phase shift with a phase characteristic of the at least one carrier so as to substantially scramble the phase characteristics of the carrier.

5. The transceiver of claim 4, wherein the phase shift is determined using a function of the carrier number.

6. The transceiver of claim 5, wherein the function of the carrier number comprises at least multiplying the carrier number by a predefined phase value.