Granted Patent B2

US 8,320,478 · App. 12/339,249 · Granted Nov 27, 2012

Abstract

Claims (21)

1. A method of generating a signal with a random low peak to average power ratio waveform for an orthogonal frequency division multiplexing system, the method comprising:

obtaining a complex vector, wherein an inverse fast Fourier transform result of the complex vector has a low peak to average power ratio real waveform;

processing the complex vector to generate a processed complex vector, wherein processing the complex vector includes one of cyclically shifting the complex vector a random amount and multiplying the complex vector by an exponential function of a product of a random imaginary number and angular frequency;

dividing the complex vector into a first vector section and a second vector section;

cyclically shifting the first vector section an amount in a direction using a linear feedback shift register to generate the cyclically shifted first vector section;

cyclically shift the second vector section in an opposite direction by a same amount to generate the cyclically shifted second vector section;

wherein the complex vector includes a plurality of elements, each of the first and second vector sections including half of the elements of the complex vector, the second vector section being a conjugate mirror of the first vector section, and the cyclically shifted second vector section being a conjugate mirror of the cyclically shifted first vector section; and

performing an inverse fast Fourier transform on the processed complex vector to generate a signal with a random low peak to average power ratio waveform of the orthogonal frequency division multiplexing system.

2. The method of claim 1 , wherein processing the complex vector includes cyclically shifting the complex vector a random amount, wherein the signal with the random low peak to average power ratio waveform includes an in phase component and a quadrature component and each of the in phase component and the quadrature component has a low random peak to average power ratio waveform.

3. The method of claim 1 further comprising multiplying the complex vector by an imaginary unit before performing the inverse fast Fourier transform on the processed complex vector.

4. The method of claim 3 , wherein the signal with the random low peak to average power ratio waveform is a purely imaginary signal.

5. The method of claim 1 further comprising multiplying the processed complex vector by an addition of a square root of one half and a product the addition of the square root of one half and the product of the square root of one half and an imaginary unit before performing the inverse fast Fourier transform on the processed complex vector.

6. The method of claim 5 , wherein the signal with the random low peak to average power ratio waveform includes an in phase component and a quadrature component and the in phase component is equal to the quadrature component.

7. The method of claim 1 , wherein the complex vector includes a plurality of elements and each element of the complex vector is generated by digital modulation using a finite constellation.

8. A system of generating a signal with a random low peak to average power ratio waveform for an orthogonal frequency division multiplexing system, the system comprising:

a vector processing unit configured to randomly process a complex vector to generate a processed complex vector, wherein an inverse fast Fourier transform result of the complex vector has a low peak to average power ratio real waveform, the vector processing unit is configured to further divide the complex vector into a first vector section and a second vector section, to cyclically shift the first vector section an amount in a direction using a linear feedback shift register to generate the cyclically shifted first vector section, and to cyclically shift the second vector section in the opposite direction by a same amount to generate the cyclically shifted second vector section, wherein the complex vector includes a plurality of elements, each of the first and second vector sections including half of the elements of the complex vector, the second vector section being the conjugate mirror of the first vector section, and the cyclically shifted second vector section being the conjugate mirror of the cyclically shifted first vector section; and

an inverse fast Fourier transforming unit configured to perform an inverse fast Fourier transform on the processed complex vector to generate a signal with a random low peak to average power ratio waveform of the orthogonal frequency division multiplexing system.

9. The system of claim 8 , wherein the vector processing unit is configured to cyclically shift the complex vector a random amount, wherein the signal with the random low peak to average power ratio waveform includes an in phase component and a quadrature component and each of the in phase component and the quadrature component has a low random peak to average power ratio waveform.

10. The system of claim 8 further comprising a multiplication unit configured to multiply the complex vector by an imaginary unit and the signal with the random low peak to average power ratio waveform is a purely imaginary signal.

11. The system of claim 8 further comprising a multiplication unit configured to multiply the processed complex vector by an addition of the square root of one half and a product of the square root of one half and an imaginary unit, wherein the signal with the random low peak to average power ratio waveform includes an in phase component and a quadrature component and the in phase component is equal to the quadrature component.

12. The system of claim 8 , wherein the complex vector includes a plurality of elements and each element of the complex vector is generated by digital modulation using a finite constellation.

Assignments (17)