FPGA Implementation of FFT Algorithm for IEEE 802.16e (Mobile WiMAX).

Abstract:

Mobile WiMAX (Worldwide Interoperability for Microwave Access) or 802.16e standard was ratified by the IEEE in late 2005 as a potential to emerge as a real viable competitor to existing 3G technologies. Mobile WiMAX uses an OFDMA™ technology called 1K-FFT. Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user version of the popular Orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. In the widely used OFDM systems, the FFT and IFFT pairs are used to modulate and demodulate the data constellation on the subcarriers. This paper presents a high level implementation of a high performance FFT for OFDM Modulator and Demodulator. The design has been coded in Verilog and targeted into Xilinx Spartan3 FPGAs. Radix-22 Algorithm is proposed and used for the OFDM communication system. This algorithm has the same multiplicative complexity as the radix- 4 algorithm, but retains the butterfly structure of radix-2 algorithm.