期刊名称：International Journal of Innovative Research in Science, Engineering and Technology
印刷版ISSN：2347-6710
电子版ISSN：2319-8753
出版年度：2014
卷号：3
期号：4
页码：11898
出版社：S&S Publications
摘要：FSO uses modulated optical focused beams toestablish atmospheric data transmission. This re-emergingtechnology combines high data rates around 2.5 Gbps incommercial implementations.This characteristic, along with highnetwork reconfigurability (provided by the short deploymenttime), license-free operation and low sensitivity toelectromagnetic interference and jamming, makes FSO systemseven more interesting for defense applications. ON-OFF keying(OOK) modulation, used by most FSO systems, is not adequateto logically hide the information, if the beam is intercepted. Thisscenario should be considered, in the case of long-haul militarymobile system with large divergence angles. Other disadvantageis that these systems are vulnerable to atmospheric phenomena,such as attenuation and scintillation. All these factors must beconsidered during the design of a new FSO system for militarypurposes.In the proposed system, encoding is done at each relaypath to protect the transmitted data from any kind of securityattack.Data security in this system comes from the physicalsignal encoding and decoding processes , because acorresponding process is required to decode the code pattern inorder to successfully receive the transmitted data. When theencoding and decoding information is kept secret, the datasecurity is ensured. Physical encoding imposes complexencoding to the physicaly transmitted signals . After the physicalencoding, the signal carrying data is transformed to anunpredictable form which is being modulated using PPMmodulation
