Conference Papers

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/28506

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Author: search.filters.author.Sripati, U.Subject: search.filters.subject.Free Space Optics (FSO)

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    Enhancement of security for free space optics based on reconfigurable chaotic technique
    (2013) Abdulameer, L.F.; Jignesh, J.D.; Sripati, U.; Kulkarni, M.
    Free Space Optical (FSO) technology offers highly directional, high bandwidth communication channels. This technology can provide fiber-like data rate over short distances. In order to improve security associated with data transmission in FSO networks, a secure communication method based on chaotic technique is presented. In this paper, we have turned our focus on a specific class of piece wise linear one-dimensional chaotic maps. Simulation results indicate that this approach has the advantage of possessing excellent correlation property. In this paper we examine the security vulnerabilities of single FSO links and propose a solution to this problem by implementing the chaotic signal generator "reconfigurable tent map". As synchronization between transmitter and receiver is essential for the correct operation of such schemes, we have also attempted to determine parameters such as auto-and cross-correlation that determine the ease with which synchronization between transmitter and receiver can be achieved. It is demonstrated that cross correlation is very close to zero and auto-correlation is δ-like. The overall system is implemented in the MATLAB Simulink Digital Signal Processing (DSP) Builder. Copyright © 2013 SPIE.
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    FPGA implementation of a BCH Codec for free space optical communication system
    (Institute of Electrical and Electronics Engineers Inc., 2014) Koila, S.; G.D., G.D.; Kulkarni, M.; Sripati, U.
    Future Free Space Optical (FSO) communication systems have the potential of communicating data at very high rates with very high levels of integrity over distances of up to a few kilometers (for terrestrial links). This technology has also been a candidate for setting up very high speed (∼3 Gbps) and highly reliable (BER ∼10-9) communication links between satellites in geo-synchronous orbits and ground stations. Since the free space optical medium can induce many forms of distortion (atmospheric turbulence effects, optical beam wander etc), the use of a channel code to detect and correct errors during the process of information transfer over the channel is essential. A correctly designed channel code can reduce the raw BER from unacceptable values to values that can be tolerated in many applications. In this paper, we have designed a Codec (encoder/decoder) pair for a (31, 16, 3) Bose, Ray-Chaudhuri, and Hocquenghem (BCH) code on the Nexys-4 FPGA platform. The performance of this BCH Codec has been tested over an indoor FSO channel and the improvement in terms of BER has been quantified. An improved syndrome computation circuit, parallel Chien search implementation and an improved method for calculating inverses in a finite field are the new features incorporated in this paper. We have been able to design and implement circuits which use these optimized approach and deliver real time encoding and decoding with an information transfer rate of 2 Mbps and can be extended upto a speed of 418Mbps. © 2014 IEEE.