Enhancing OFDM Performance Using Wavelet Transform Techniques in Wireless Systems

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) technique has attracted major interest because of its robustness to time selective channels and its aptitude to accomplish high data rate. OFDM is the fundamental solution in 4G and 5G systems due to its simplicity of implementation and effectiveness in severe environments. Traditionally the Fast Fourier Transform (FFT) algorithm is adopted to implement OFDM transmitter. Discrete Wavelet Transform (DWT) is recognized as an improvement to Discrete Fourier Transform; therefore, many academics proposed it as alternative approach to FFT in OFDM transmission system. We propose to study the impact of DWT on the performance of the OFDM transmission system considering various modulation techniques and order in noisy and fading environments. We implement two approaches namely OFDM-FFT and OFDM-DWT, their performances respective are studied and compared. Through simulation examples, we notice the improvements obtained by performing the wavelet transform. The wavelet-based OFDM techniques perform better than OFDM-FFT. The results obtained demonstrate the improvements achieved by adopting the wavelet transform relatively to the FFT for all evaluation metrics used. OFDM-DWT cancels interferences, as we can learn from constellation diagrams, where symbols are delimited in their original zones. OFDM-DWT performs the lowest bit error rate (BER) and a reduced Complementary Cumulative Distribution Function (CCDF) of the Peak to Average Power Ratio (PAPR).