基于FPGA的OFDM调制器的设计

提出了一种新的流水线FFT设计方法来实现OFDM调制解调:利用旋转因子对称性、简化的复数乘法和旋转因子CSD编码来简化蝶形单元设计,并按照读修改地址写的顺序,利用双口RAM从一级向下一级来传送数据.该方法实现蝶形运算不需要乘法器、不需要ROM来存储旋转因子,需要的RAM单元也比较少.最后用该方法在FPGA上实现8pt基2的DIFFFT处理器,实验证明该方法在硬件资源消耗上有很大的改善.

Design of OFDM Modulator Base on FPGA

In this paper, the authors propose a novel method to design pipelined FFT for the implementation of OFDM modulator/demodulator. The symmetry characteristic of twiddle factors, simplified multiplication of complex number and CSD coding of twiddle factors are used to simplify the hardware implementation of butterfly. Data are transmitted from one stage to the next through the dpram according to the order: read-modify address-write. No multiplication is needed to implement butterfly, no ROM is needed to store twiddle factors or fewer RAM is required. A 8pt DIF FFT is realized in FPGA and the result demonstrates the method has great improvements in hardware size.