Design, development and Performance Analysis Of 8-point FFT chip using VHDL for OFDM Applications

Abstract: In several wired and wireless applications high-speed performance is required, which is only possible by using conventional multi-carrier transmission techniques, but this will results in the lowering of spectrum efficiency. So, in such applications the principle of Orthogonal Frequency Division Multiplexing (OFDM) is used. This paper gives the details of the design, development and performance analysis of 8-point FFT algorithms to be used in OFDM systems based on the IEEE 802.11a standard for WLAN. Generally, the inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT) operations are used as the modulation and demodulation in the OFDM systems, and the sizes of FFT/IFFT are varied in various applications of OFDM systems. Actually, in the complete architecture of OFDM system, all the mathematical manipulations take place in IFFT & FFT blocks while remaining blocks convert the data from one format to another format. VHDL programming language is used to develop the design and synthesized on Virtex-5 FPGA in Xilinx 14.2 software and Modelsim 10.1 is used for functional simulation.

Keywords: Fast Fourier Transform (FFT), Inverse Fast Fourier Transform (IFFT), Orthogonal Frequency Division Multiplexing (OFDM), Hardware Description Language (HDL).