77,669 research outputs found
Design of Energy-Efficient Artificial Noise for Physical Layer Security in Visible Light Communications
This paper studies the design of energy-efficient artificial noise (AN)
schemes in the context of physical layer security in visible light
communications (VLC). Two different transmission schemes termed
and
are examined and
compared in terms of secrecy energy efficiency (SEE). In the former, the
closest LED luminaire to the legitimate user (Bob) is the information-bearing
signal's transmitter. At the same time, the rest of the luminaries act as
jammers transmitting AN to degrade the channels of eavesdroppers (Eves). In the
latter, the information-bearing signal and AN are combined and transmitted by
all luminaries. When Eves' CSI is unknown, an indirect design to improve the
SEE is formulated by maximizing Bob's channel's energy efficiency. A
low-complexity design based on the zero-forcing criterion is also proposed. In
the case of known Eves' CSI, we study the design that maximizes the minimum SEE
among those corresponding to all eavesdroppers. At their respective optimal
SEEs, simulation results reveal that when Eves' CSI is unknown, the selective
AN-aided SISO transmission can archive twice better SEE as the AN-aided MISO
does. In contrast, when Eves' CSI is known, the AN-aided MISO outperforms by
30%
Secure thermal infrared communications using engineered blackbody radiation
The thermal (emitted) infrared frequency bands, from 20–40 THz and 60–100 THz, are best known for applications in thermography. This underused and unregulated part of the spectral range offers opportunities for the development of secure communications. The ‘THz Torch' concept was recently presented by the authors. This technology fundamentally exploits engineered blackbody radiation, by partitioning thermally-generated spectral noise power into pre-defined frequency channels; the energy in each channel is then independently pulsed modulated and multiplexing schemes are introduced to create a robust form of short-range secure communications in the far/mid infrared. To date, octave bandwidth (25–50 THz) single-channel links have been demonstrated with 380 bps speeds. Multi-channel ‘THz Torch' frequency division multiplexing (FDM) and frequency-hopping spread-spectrum (FHSS) schemes have been proposed, but only a slow 40 bps FDM scheme has been demonstrated experimentally. Here, we report a much faster 1,280 bps FDM implementation. In addition, an experimental proof-of-concept FHSS scheme is demonstrated for the first time, having a 320 bps data rate. With both 4-channel multiplexing schemes, measured bit error rates (BERs) of < 10(−6) are achieved over a distance of 2.5 cm. Our approach represents a new paradigm in the way niche secure communications can be established over short links
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