In this paper, a proposed structure was suggested by replacing the blocks of the fast Haar Wavelet Transform (WT) with a two dimensional wavelet transform at the transmitter and the receiver sides in the Orthogonal Frequency Division Multiplexing (OFDM) model. This can be done by converting a 1-Dimensional vector into a 2-Dimensional matrix and process it by 2-Dimensional Wavelet Transform (2D-WT). The proposed method was applied on the OFDM in Additive White Gaussian Noise (AWGN) and flat fading channel. It was concluded that the proposed method gives much better Bit Error Rate (BER) performance than the conventional OFDM model based on WT. The simulation results showed that the proposd structure outperforms the other scheme in the carried tests at the AWGN and flat fading channels.
This paper proposes an efficient algorithm for fast computation of the inverse real-valued discrete Fourier transform (IRDFT) using the decimation in frequency (DIF) approach. The proposed algorithm represents a direct method with a new implementation for fast computing of IRDFT. The algorithm derivation is based on the basic principles of the Cooley-Tukey algorithm with the divide and conquer approach and utilizes the advantage of conjugate symmetric property for the discrete Fourier transform (DFT) to remove all redundancies that appear when DFT deals with real data. The analyses of the proposed algorithm have shown that the arithmetic number has reached a minimum, therefore the structure of the developed algorithm possesses the desired properties such as regularity, simplicity, and in-place computation. The arithmetic complexity of this algorithm has been compared with the inverse FFT algorithm, and it was found that it needs the least number of multiplications and additions. The validity of the developed algorithm has been verified by reducing the peak-to-average power ratio PAPR in optical-OFDM systems compared with complex FFT. The simulation using MATLAB(R2021a) findings show that the RFFT O-OFDM system reduces PAPR more efficiently than the FFT O-OFDM system. The PAPR exhibits a reduction of approximately 2.4 to 2.75 dB when evaluated at a probability of occurrence of 10-1 in the complementary cumulative distribution function (CCDF) plot.
WMAN (wireless metropolitan area network) technology is based on the IEEE 802.16 air interface standard suite, which provides the wireless technology for fixed and nomadic data access. WMAN employs orthogonal frequency division multiplexing (OFDM), and supports adaptive modulation and coding depending on the channel conditions. The objective of this paper is to study the performance of the IEEE 802.16d WMAN physical layer under Nakagami model as a Multi-path and frequency-selective fading channel beside the additive white Gaussian noise (AWGN) and Doppler. Finally, we compared it with the Rayleigh fading model. The transmission bit rate, Probability of Error ( ) and estimated SNR have been compared under single/multi path propagation conditions.