OFDM Systems Design Using Harmonic Wavelets

Abstract

Orthogonal frequency-division multiplexing (OFDM) is a popular multi-carrier technique used in many digital communication systems such as wireless fidelity (Wi-Fi), long term evolution (LTE) and power line communication systems. It can be designed using fast Fourier transform (FFT) or wavelet transform (WT). The major drawback in using WT is that it is computationally inefficient. In this study, we introduce a simple and computationally efficient WT, harmonic wavelet transform, for OFDM signal processing. The new WT uses the orthogonal basis functions of conventional FFT-OFDM except that it involves translation and dilation of the input signal; the new wavelets is referred to as harmonic wavelets (HW). When compared with pilot-assisted OFDM system in terms of reduction in the peak-to-average power ratio, the results show that HW-OFDM outperforms FFT-OFDM by 3 dB at 10 −4 CCDF (complementary cumulative distribution function). Over Rayleigh fading channel with additive white Gaussian noise (AWGN), the bit error ratio of both FFT-OFDM and HW-OFDM perfectly matched, showing that the proposed HW-OFDM is better in terms of peak-to-average power ratio reduction.

Design and optimisation of high‐efficient class‐F ULP‐PA using envelope tracking supply bias control for long‐range low power wireless local area network IEEE 802.11ah standard using 65 nm CMOS technology

“…Discrete Wavelet Transform detects the harmonics at the instantaneous level and for the elimination of noise before the harmonics [33]. Study [32] proposed Harmonic Wavelets (HW)‐OFDM is a preferable over FFT‐OFDM in terms of estimating PAPR reduction. In OFDM, the parameters of each frequency component can be accurately analysed if it satisfies the Nyquist sampling theorem.…”

“…For a conventional OFDM, on the spot detection of OFDM harmonics was performed by Fast Fourier Transform method. The considerable imperfection in using traditional Wavelet Transform (WT) is that it is computationally inefficient [32]. In recent years, numerous advanced methods, in the areas of digital communication, have been introduced for detection of OFDM harmonics.…”