基于改进FFT算法的OFDM调制/解调模块设计  

The Design of a Modular OFDM Modulate/Demodulate Module

作　　者：廖巨华[1,2,3] 陈岚[1] 

机构地区：[1]中国科学院计算技术研究所 [2]中国科学院研究生院,北京100080 [3]苏州中科集成电路设计中心,苏州215021

出　　处：《微电子学与计算机》2005年第6期57-60,共4页Microelectronics & Computer

基　　金：国家自然科学基金资助(NSFC60203006)

摘　　要：文章对传统FFT算法进行了改进,改进后的算法将N点DFT分解成二维姨N点DFT的组合,在结构上更适合于用流水线方式实现FFT。文章首先对算法进行了推导,然后基于该算法设计了一个64点、32位字长的定点IFFT/FFT模块,用于802.11a中OFDM的调制/解调。与传统的流水线FFT比较,该模块中的复数乘法运算全部采用移位相加操作完成,因而消除了乘法器及旋转因子ROM的使用,降低了功耗。最后,对该模块进行了验证仿真。结果表明,在流水线饱和的情况下,该模块完成一个64点的FFT运算只需要8个时钟周期,在20MHZ时钟频率下,该模块的功耗为0.26W,完全能满足移动通信中对于高速度、低功耗的要求。This article presented an improved FFT algorithm. The algorithm, which decomposes N-point DFT into -point DFT, was structurally more suitable for the pipeline implementation of FFT. The algorithm was deduced first, then a 64-point?32-bit fixed-point pipeline IFFT/FFT module was designed based on the algorithm. In comparison with traditional pipeline FFT, the complex multiplication was implemented by shifting and addition operations in order to eliminate multiplication unit and coefficient ROM. Finally, the module was verified and simulated. The results showed that in condition that the pipeline was saturating, only 8 clock cycles were needed to finish a 64-point DFT. Under 20 MHz frequency, the power consumption of the module was 0.26W. As a result, the FFT module could satisfy both high speed and low power requirements for mobile applications.

关 键 词：正交频分多路复用 流水线 快速付立叶变换 调制/解调 低功耗 

分 类 号：TP393.02[自动化与计算机技术—计算机应用技术]