Performance Analysis and Implementation of FFT and DWT OFDM

Authors : Shashidhara K.S., Badrala Sri Pavan

Abstract

In present day broadband communication system the ever-increasing demand is found for digital multimedia applications. In turn wireless communication systems require staggeringly tremendous data rates and high transmission reliability for multimedia applications such as high quality audio and video. The mobile communication is expanding tremendously with growing technology and is one of the best outcome of the wireless communications. With this expansion, demand emerges an augmenting need to transmit information wirelessly, expeditiously and precisely. Existing wireless technologies cannot afford these requirements since they are very sensitive to fading. Orthogonal Frequency Division Multiplexing (OFDM) is one of the promising modulation techniques to meet the above requirements. OFDM is a method that allows us to transmit high data rates over wireless noisy channels (i.e. delay dispersive environments) at a comparable low complexity. In this project we discuss the performance evaluation results of implementation of Fast Fourier Transform (FFT) and Discrete Wavelet Transform (DWT) for OFDM systems. FFT-OFDM system utilizes the Cyclic Prefix (CP) to mitigate the Inter Symbol Interference (ISI). DWT-OFDM system due to overlapping nature of its properties, it doesn’t need CP, thereby increases bandwidth efficiency by 25% [14]. The results obtained shows that probability of error (i.e., Bit Error Rate (BER)) in DWT-OFDM scheme is improved in many scenarios. The system is modelled using Simulink and the functionality has been verified by implementing on FPGA.

KEYWORDS : BER (Bit Error Rate), DWT, FFT, OFDM.