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FFT (Fast Fourier Transform)/IFFT (Inverse Fast Fourier Transform) device based on LTE (Long Term Evolution) system

A transformation device and complex number technology, applied in the field of FFT/IFFT transformation devices, can solve the problems of multi-storage resources, consumption, inability to support block floating-point FFT/IFFT transformation, etc.

Active Publication Date: 2016-06-01
WUHAN HONGXIN TELECOMM TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For the six conversion points required by the LTE system, mainstream FPGA manufacturers such as XILINX and ALTERA have provided solutions based on their respective FFT / IFFT IP cores, but their common defect is that they cannot use only one IP core to meet both requirements. These six kinds of transmission bandwidth requirements can also be processed by block floating-point FFT / IFFT. The patent "A 1536-point FFT / IFFT Realization Method and Device" (application number: 200910172964.3) proposes a 1536-point FFT / IFFT realization method And devices, cannot support block floating-point FFT / IFFT transformation, and need to use and store 1536 twiddle factors, which will undoubtedly consume more storage resources

Method used

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  • FFT (Fast Fourier Transform)/IFFT (Inverse Fast Fourier Transform) device based on LTE (Long Term Evolution) system
  • FFT (Fast Fourier Transform)/IFFT (Inverse Fast Fourier Transform) device based on LTE (Long Term Evolution) system
  • FFT (Fast Fourier Transform)/IFFT (Inverse Fast Fourier Transform) device based on LTE (Long Term Evolution) system

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Embodiment Construction

[0037] The technical principle that the present invention is based on is as follows:

[0038] Let the length N=512*r of the sequence x(n) to be subjected to discrete Fourier transform (DFT), sequence index n=r*n 1 +n 0 , where n 1 =0,1,2,...511, n 0=0,1,2,...r-1; Let the length N=r*51 of the transformed sequence X(k), 2 index k=512*k 1 +k 0 , where k 1 = 0, 1, 2, ... r-1, k 0 =0,1,2,...511, let N be equal to 1024, 1536 and 2048 respectively and substitute into the DFT relation The DFT relational expressions of 1024, 1536, and 2048 points obtained by expansion are shown in the following formulas (1)-(3):

[0039] X ( 512 * k 1 + k 0 ) = [ Σ n 1 = 0 511 ...

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Abstract

The invention discloses an FFT (Fast Fourier Transform) / IFFT (Inverse Fast Fourier Transform) device based on an LTE (Long Term Evolution) system. According to the FFT / IFFT device disclosed by the invention, six kinds of transformation points defined by the LTE system are divided into two kinds: smaller transformation points (128, 256 and 512) are all integer power of 2 and can be directly subjected to corresponding FFT / IFFT, and larger transformation points (1024, 1536 and 2048) are all realized based on 512-point FFT or IFFT and r-based operation, so that the structure is simple, the resource of multiplying units and summing units which are needed is less, and compared with the prior art, not only can six kinds of transmission bandwidth processing be supported, but also block-floating point FFT / IFFT can be supported; only 512 twiddle factors need to be used and memorized for executing 1536-point FFT / IFFT, and only 1536 twiddle factors are needed to be totally memorized for executing 1024-, 1536- and 2048-point FFT / IFFT, so that the resource occupation is reduced.

Description

technical field [0001] The invention relates to the field of digital signal processing and the field of communication, in particular to an FFT / IFFT conversion device based on an LTE system. Background technique [0002] The LTE system uses a sub-carrier bandwidth of 15KHz. By setting different numbers of sub-carriers, more precisely, they are mapped to different resource block (PRB) numbers to achieve a variable system bandwidth from 1.4MHz to 20MHz. The LTE system defines 6 different system bandwidth. The number of DFT / IDFT transformation points corresponding to these six transmission bandwidths are 128, 256, 512, 1024, 1536 and 2048 respectively. For the six conversion points required by the LTE system, mainstream FPGA manufacturers such as XILINX and ALTERA have provided solutions based on their respective FFT / IFFT IP cores, but their common defect is that they cannot use only one IP core to meet both requirements. These six kinds of transmission bandwidth requirements ...

Claims

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Application Information

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IPC IPC(8): G06F17/14
CPCG06F17/14
Inventor 华虎军
Owner WUHAN HONGXIN TELECOMM TECH CO LTD