A Hybrid Cybersecurity Algorithm for Digital Image Transmission over Advanced Communication Channel Models

The efficient transmission of images, which plays a large role in wireless communication systems, poses a significant challenge in the growth of multimedia technology. High-quality images require well-tuned communication standards. The Single Carrier Frequency Division Multiple Access (SC-FDMA) is adopted for broadband wireless communications, because of its low sensitivity to carrier frequency offsets and low Peak-to-Average Power Ratio (PAPR). Data transmission through open-channel networks requires much concentration on security, reliability, and integrity. The data need a space away from unauthorized access, modification, or deletion. These requirements are to be fulfilled by digital image watermarking and encryption. This paper is mainly concerned with secure image communication over the wireless SC-FDMA system as an adopted communication standard. It introduces a robust image communication framework over SC-FDMA that comprises digital image watermarking and encryption to improve image security, while maintaining a high-quality reconstruction of images at the receiver side. The proposed framework allows image watermarking based on the Discrete Cosine Transform (DCT) merged with the Singular Value Decomposition (SVD) in the so-called DCT-SVD watermarking. In addition, image encryption is implemented based on chaos and DNA encoding. The encrypted watermarked images are then transmitted through the wireless SC-FDMA system. The linear Minimum Mean Square Error (MMSE) equalizer is investigated in this paper to mitigate the effect of channel fading and noise on the transmitted images. Two subcarrier mapping schemes, namely localized and interleaved schemes, are compared in this paper. The study depends on different channel models, namely Pedestrian A and Vehicular A, with a modulation technique named Quadrature Amplitude Modulation (QAM). Extensive simulation experiments are conducted and introduced in this paper for efficient transmission of encrypted watermarked images. In addition, different variants of SC-FDMA based on the Discrete Wavelet Transform (DWT), Discrete Cosine Transform (DCT), and Fast Fourier Transform (FFT) are considered and compared for the image communication task. The simulation results and comparison demonstrate clearly that DWT-SC-FDMA is better suited to the transmission of the digital images in the case of Pedestrian A channels, while the DCT-SC-FDMA is better suited to the transmission of the digital images in the case of Vehicular A channels.