FFT/IFFT device and method based on LTE system

Abstract

The invention discloses an FFT / IFFT device and method based on an LTE system. Six transformation point numbers defined by the LTE system are divided into two classes, namely, small transformation point numbers (128, 256 and 512) and large transformation point numbers (1024, 1536 and 2048), wherein the small transformation point numbers are all 2 of integer power, and corresponding FFT / IFFT is directly carried out; the large transformation point numbers are all realized based on 512-point FFT / IFFT and r-base operation. The structure is simple, and few multiplier and summator resources are needed; compared with the prior art, processing with six transmission bandwidths can be supported at the same time, and block-floating-point FFT / IFFT can also be supported. In addition, only 512 twiddle factors need to be used and stored in the process of executing 1536-point FFT / IFFT, only 1536 twiddle factors need to be stored in total in the process of executing 1024-point FFT / IFFT, 1536-point FFT / IFFT and 2048-point FFT / IFFT, and thus 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 and method 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 6 different subcarriers defined by the LTE system The corresponding relationship between the system bandwidth and the number of subcarriers and the number of PRBs is as follows: [0003] [0004] The numbers of DFT / IDFT transformation points corresponding to the above 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 F...

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

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