Publications

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The wireless communications channel is innately insecure due to the broadcast nature of the electromagnetic medium. Many techniques have been developed and implemented in order to combat insecurities and ensure the privacy of transmitted messages. Traditional methods include encrypting the data via cryptographic methods, hiding the data in the noise floor as in wideband communications, or nulling the signal in the spatial direction of the adversary using array processing techniques. This work analyzes the design of signaling constellations, i.e. modulation formats, to combat eavesdroppers from correctly decoding transmitted messages. It has been shown that in certain channel models the ability of an adversary to decode the transmitted messages can be degraded by a clever signaling constellation based on lattice theory. This work attempts to optimize certain lattice parameters in order to maximize the security of the data transmission. These techniques are of interest because they are orthogonal to, and can be used in conjunction with, traditional security techniques to create a more secure communication channel.

Communication using mid-ultraviolet radiation between 200nm and 280nm has received renewed attention due to advancements in UV LED emitters and unique propagation characteristics at these wavelengths. Atmospheric gases absorb light at mid-UV so that receivers or sensors operating on the earth's surface receive no interference from solar radiation. This so-called 'solar-blind' region of the spectrum allows the use of single-photon detection techniques. Further, UV light is strongly scattered by molecules in the air, enabling non-line-of-sight (NLOS) communication. We extend previous work in this area by incorporating angle-dependent Mie scattering into one of the standard propagation models, in an effort to include the effects of aerosols. Experimental results from outdoor measurements using a fog generator are also presented. © 2012 IEEE.

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