Development of new model for multiwavelet-based OFDM over wireless channel and its implementation in FPGA

Abstract

Orthogonal Frequency-Division Multiplexing (OFDM) has been widely utilized in the field of high speed communication systems, due to its prominent features. However, it is prone to impairments such as Inter-Symbol Interference (ISI), Inter-Carrier Interference (ICI), and high Peak-to-Average Power Ratio (PAPR). Moreover, the Guard Interval (GI), which is inserted between the OFDM symbols, will take up nearly 25% of the bandwidth, decreasing the data rate and increasing the system‟s complexity. To mitigate for these impairments, a new OFDM based on Discrete Multiwavelet Critical-Sampling Transform (OFDM-DMWCST) model (Model 1) has been proposed in this work. The theoretical analysis proved that the OFDM-DMWCST model has higher bandwidth efficiency and less computational complexity compared to other OFDM systems utilizing Discrete Multiwavelet Over-Sampling Transform (DMWOST), Discrete Wavelet Transform (DWT), and Fast Fourier Transform (FFT). The simulation results showed that the OFDM-DMWCST provides better Bit Error Rate (BER) performance among all OFDM systems over different channel models, namely, Additive White Gaussian Noise (AWGN), flat fading, and frequency-selective fading. For instance, in the frequency-selective fading channel with 4-QAM mapping, at BER = 10-3, the OFDM-DMWCST reported a 1.5 dB and 14.2 dB gain in Signal-to-Noise Ratio (SNR) over OFDM based on DWT and OFDM based on FFT, respectively, while the OFDM based on DMWOST failed to realize such a BER value. Also, the OFDMDMWCST model can realize better PAPR reduction compared to the traditional OFDM model. Moreover, a hybrid technique, consisting of FFT and Sliding Window (SW) algorithm, has been proposed for the development of a new model for OFDMDMWCST and render it more suitable for outdoor applications.