Device and method for fast fourier transform

1. A method for Fast Fourier Transform (FFT), the method comprising: duplicating M/N copies of input data and storing the M/N copies into M/N different addresses of a memory, then performing M-point FFT on stored data in a FFT unit, and extracting one point in every several points in transformed data and outputting extracted data, and said M being a maximum number of points in the FFT, N being a practical number of points in the input data, thus to implement multiplexing of the FFT, wherein M=2 n+j , N=2 n , n is a natural number greater than 0, j=0, 1, 2, M and N are integers.

2. The method of claim 1 , wherein,

before the storing step, the method also comprises: judging whether to perform the M-point FFT on the input data at first, and if yes, performing the M-point FFT on the input data directly and outputting the transformed data, otherwise, carrying out the storing step.

3. The method of claim 1 , wherein, when M=2N, the step of duplicating two copies of the input data and storing the two copies into two different memory addresses is: duplicating two copies of i th data and storing the two copies into the memory addresses i and N+i respectively; wherein i is a natural number, 0≦i≦N−1.

4. The method of claim 1 , wherein,

when M=4N, the step of duplicating four copies of the input data and storing the four copies into four different memory addresses is: duplicating four copies of i th data and storing the four copies into the memory addresses i, N+i, 2N+i, and 3N+i respectively, wherein i is a natural number , 0≦i≦N−1.

5. The method of claim 3 , wherein,

in the step of extracting one point in every several points in the transformed data, extract (2i) th data or (2i+1) th data, where 0≦i≦N−1.

6. The method of claim 4 , wherein,

in the step of extracting one point in every several points in the transformed data, extract (4i) th data, or (4i+1) th data, or (4i+2) th data or (4i+3) th data, where 0≦i≦N−1.

7. A device for Fast Fourier Transform (FFT), comprising: a data receiver, a data storage memory, a FFT unit, and a data output; said device also comprising a memory address translation unit and a data extraction unit;

said data receiver module being configured to: receive input data;

said address translation unit being configured to: duplicate M/N copies of received data and sending the copies to the data storage memory;

said data storage memory being configured to: store the received data sent from the memory address translation unit to M/N different addresses of the memory;

said FFT unit being configured to: perform M-point FFT on stored data;

said data extraction unit is configured to: extract one point in every several points in transformed data and sending extracted data to the data output;

said data output is configured to: output the received data;

said M being a maximum number of points in the FFT, and N being a practical number of points in the input data;

thereby, multiplexing of the FFT being completed; wherein M=2 n+j , N=2 n ,n is a natural number greater than 0, j=0, 1, 2, M and N are integers.

8. The device of claim 7 , wherein,

said device also comprises a judgment unit, and said judgment unit is configured to: after receiving data sent from the data receiver, judge whether to perform M-point FFT or not, and if yes, send the data to the storage memory, otherwise, send the data to the memory address translation unit.

9. The device of claim 7 , wherein,

said data storage memory is configured to: when M=2N, store duplicated i th data to the memory addresses i and N+i respectively; wherein i is a natural number, 0≦i≦N−1;

or, said data storage memory is configured to: when M=4N, store the duplicated i th data to the memory addresses i, N+i, 2N+i, and 3N+i respectively; wherein i is a natural number, 0≦i≦N−1.

10. The device of claim 9 , wherein,

said data extraction unit is configured to: when M=2N, extract (2i) th data or (2i+1) th data, where 0≦i≦N−1;

or, said data extraction unit is configured to: when M=4N, extract (4i) th data, or (4i+1) th data, or (4i+2) th data or (4i+3) th data, where 0≦i≦N−1.