Free-space 16-ary orbital angular momentum coded optical communication system based on chaotic interleaving and convolutional neural networks

Abstract

Recently, orbital angular momentum (OAM) rays passing through free space have attracted the attention of researchers in the field of free-space optical communication systems. Throughout free space, the OAM states are subject to atmospheric turbulence (AT) distortion leading to crosstalk and power discrepancies between states. In this paper, a novel chaotic interleaver is used with low-density parity-check coded OAM-shift keying through an AT channel. Moreover, a convolutional neural network (CNN) is used as an adaptive demodulator to enhance the performance of the wireless optical communication system. The detection process with the conjugate light field method in the presence of chaotic interleaving has a better performance compared to that without chaotic interleaving for different values of propagation distance. Also, the viability of the proposed system is verified by conveying a digital image in the presence of distinctive turbulence conditions with different error correction codes. The impacts of turbulence strength, transmission distance, signal-to-noise ratio (SNR), and CNN parameters and hyperparameters are investigated and taken into consideration. The proposed CNN is chosen with the optimal parameter and hyperparameter values that yield the highest accuracy, utmost mean average precision (MAP), and the largest value of area under curve (AUC) for the different optimizers. The simulation results affirm that the proposed system can achieve better peak SNR values and lower mean square error values in the presence of different AT conditions. By computing accuracy, MAP, and AUC of the proposed system, we realize that the stochastic gradient descent with momentum and the adaptive moment estimation optimizers have better performance compared to the root mean square propagation optimizer.

Performance Analysis of 3D Video Transmission Over Deep-Learning-Based Multi-Coded N-ary Orbital Angular Momentum FSO System

“…In addition, the control of the initial beam-field amplitude is useful for weakening the scrambling of the OAMmode [22]. In our previous work [23], an alternative effectual CNN architecture designed on the basis of the trial-and-error approach till getting the optimum network parameter and hyperparameter values was introduced. It yields the highest accuracy and mean average precision (MAP), and the largest area under the curve (AUC) value for the different optimizers.…”

“…However, in this work, compared to our previous work [23], multiple error correction and detection codes with 3D CI technique are used to improve the efficiency of VF communication via the N -OAM-SK-FSO model. Two effective DL techniques, namely CRNN and 3DCNN are used as adaptive demodulators and a study of the different performance metrics of them is presented using multiple datasets.…”

Efficient and Secure Bit-Level Chaos Security Algorithm for Orbital Angular Momentum Modulation in Free-Space Optical Communications

“…The simulation results and performance analysis in [38] reveal that this algorithm is effective and reliable for image encryption. Our previous work in [54] introduced an alternative effectual CNN architecture that is designed based on trial-and-error approach till getting the optimum network parameter and hyperparameter values to yield the best performance metrics of deep learning with three different optimizers. The objective is to obtain the optimal model through the 16 OAM-SK-FSO system using a 2D chaotic interleaver with Turbo and LDPC coded images.…”

“…where χ(r, ∅, z) is the Laguerre Gaussian (LG ) beam spatial distribution, and the equation that is used to measure ABER in the simulation analysis is, given by [8], [54]:…”

“…where E is a normalization constant, r is the radial distance from z, l is the intertwined helical phase front, p is the radial index, (r, φ, z) are the cylindrical coordinates, Υ = 2π/λ is the wave number, λ is the optical wavelength, and L p |l| is the generalized Laguerre polynomial. At a distance z, the beam radius of the standard Gaussian beam is given by [54]:…”