Faculty Publications
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Item Performance of Orthogonal and Non-Orthogonal Space Time Block Code Through the Underwater Wireless Optical Channels(IEEE Computer Society, 2023) Naik, R.P.; Mans, R.; Shripathi Acharya, U.; Savidhan Shetty, C.S.Multiple input multiple output (MIMO) schemes have been integrated with the space-time (ST) codes to enhance the reliability of information transfer across the wireless channel. Due to their rich algebraic structure, space time block codes (STBCs) such as orthogonal STBCs (OSTBC), quasi-orthogonal STBC (QOSTBC), and non-orthogonal STBCs (NOSTBC), offer efficient implementation of a reliable communication system. The underwater wireless optical communication (UWOC) channel is perturbed by the weak turbulence and fading (referred as scintillation), and shares many properties with a wireless channel. In this paper, we have designed OSTBC/QOSTBC and NOSTBC schemes for UWOC system, which can significantly improve the integrity of information transfer across the underwater optical wireless channels. These codes have been suitably conditioned to operate with an UWOC system employing intensity modulation. Monte-Carlo bit error rate simulations of the proposed schemes are plotted and presented with respect to the available transmit power in dB. © 2023 IEEE.Item Performance investigation of underwater wireless optical system for image transmission through the oceanic turbulent optical medium(Springer, 2022) Naik, R.P.; Shripathi Acharya, U.S.; Lal, S.; Krishnan, P.The importance of resources contained in the sea and on the sea floor is increasing with each passing day. Hence, exploration of the sea and sea floor has become a very important requirement. Underwater imaging is a science that has gained importance over the past two decades. Underwater images indicate the state of sea floor and transmitting such images through the harsh and turbulent oceanic medium can cause deterioration of the information contained in the image due to diminished color reproduction, low contrast and blur. In this paper, we have performed the simulation studies to understand perturbations induced during the transmission of sea floor images using high-speed optical signaling through the underwater channels. The transmitted irradiance often suffers from underwater turbulence and beam attenuation. The bit error rate (BER) of the system proposed to transmit information through channels has been determined through analytic means and validated through Monte-Carlo simulation. Comparison between the transmitted and received images in the presence of turbulence and attenuation have been presented. The BER performance of the proposed system is evaluated in the presence of beam attenuation and underwater turbulence. The turbulence induced errors are minimized using the transmit/receive diversity and multiple input multiple output (MIMO) techniques. In addition to the diversity techniques, median and adaptive median filters used to minimize the distortion in the received image. The BER results show that the 4 × 5 MIMO system gains 19.50 dB of transmit power at BER of 10 - 5, when compared with the single input single output system. Similarly, an improvement of at-least 18 dB peak signal to noise ratio obtain using the adaptive median filter based system over the un-filter based system. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.