Abstract
The paper proposes a novel technique for reducing noise in M-ary signal transmission through wireless fading channel using wavelet denoising that play the key role. The paper also explains that the conventional threshold-based technique is not capable of denoising M-ary quadrature amplitude modulated (M-QAM) signals having multilevel wavelet coefficients through wireless fading channels. A detailed step by step wavelet decomposition and reconstruction processes are discussed here to transform a signal function into wavelet coefficients using simulation software like MATLAB. A 16-QAM modulated symbol through a Rician fading channel is weighted by a control variable of complex form to force the mean of each detail coefficient except low frequency component to zero to enhance noiseless property. The bit error rate (BER) performance of the simulation results are furnished to show the effectiveness of the proposed technique. The root mean square of the deviation of the reconstruct signal from the original signal is used to express the effectiveness of the proposed technique. The traditional denoising provides very high value (above 90%) of the percentage root mean square difference (PDR) and the proposed technique provides only 10% PDR value for the symbol through a noisy channel. The result of the simulation study reveals that the BER performance can be increased using an appropriate control variable to force the mean of each detail coefficient to zero.
Highlights
Introduction and Literature ReviewThe signal transmitted through a wireless channel may arrive at the receiver through a number of paths with different amplitude, phase, and time delay due to multipath fading
A robust wavelet denoising-based estimator using a robust loss function is used to denoise a wireless signal through a Gaussian noisy channel [14]
The simulation study reveals that the proposed technique provides better bit error rate (BER) performance of M-ary signal for a multipath fading channel, depending on the weighting control variables
Summary
The signal transmitted through a wireless channel may arrive at the receiver through a number of paths with different amplitude, phase, and time delay due to multipath fading. The authors attempt to apply wavelet decomposition technique to generate wavelet coefficients of a noisy signal passing through a fading channel. The reconstruction of the original symbol from the noisy transmitted symbol through the fading channel using wavelet denoising technique is discussed in detail in this paper. The problem of the traditional denoising is that the wavelet coefficients of 16-QAM or 64-QAM modulated symbols consist of multiple-bits and the thresholding technique is not able to estimate the noisy coefficients either greater or less than the threshold value. The simulation study reveals that the proposed technique provides better BER performance of M-ary signal for a multipath fading channel, depending on the weighting control variables.
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