LTE系统中可配置FFT/IFFT的设计与实现

Design and implementation of configurable FFT/IFFT in the LTE system

针对3GPP长期演进(LTE)系统中载波数目可变以及存在非2n点的特点,提出了一种点数可变、支持非2n点的快速傅里叶变换/逆变换(FFT/IFFT)设计方案.通过采用流水线乒乓结构,利用基2、基3、基4混合基结构实现了高速可配置的FFT/IFFT.将旋转因子统一存储,同时对地址生成单元进行优化,使输入、输出数据共用RAM,可以节约100 kbit左右的存储空间.仿真和综合结果表明,该设计方案满足LTE高速系统中各种带宽下FFT/IFFT的要求.

A design of the variable-point FFT/IFFT for non-2n is proposed in consideration of the characteristics of the variable-length and non-2n subcarriers in the 3GPP LTE system.A high speed and configurable FFT/IFFT is designed by using the mixed radix with radix-2,radix-3,and radix-4 based on the pipelined ping-pong architecture.It will save about 100 kbits storage space since all the twiddle factors are stored in the same space and RAM is shared by I/O data after optimizing the address generation unit.Simulation results show that the design can satisfy the need of the FFT/IFFT for different bandwidths in a high-speed LTE system.