2 research outputs found
Relay-Aided Secure Broadcasting for Visible Light Communications
A visible light communication broadcast channel is considered, in which a
transmitter luminaire communicates with two legitimate receivers in the
presence of an external eavesdropper. A number of trusted cooperative
half-duplex relay luminaires are deployed to aid with securing the transmitted
data. Transmitters are equipped with single light fixtures, containing multiple
light emitting diodes, and receiving nodes are equipped with single
photo-detectors, rendering the considered setting as a single-input
single-output system. Transmission is amplitude-constrained to maintain
operation within the light emitting diodes' dynamic range. Achievable secrecy
rate regions are derived under such amplitude constraints for this
multi-receiver wiretap channel, first for direct transmission without the
relays, and then for multiple relaying schemes: cooperative jamming,
decode-and-forward, and amplify-and-forward. Superposition coding with uniform
signaling is used at the transmitter and the relays. Further, for each relaying
scheme, secure beamforming vectors are carefully designed at the relay nodes in
order to hurt the eavesdropper and/or benefit the legitimate receivers.
Superiority of the proposed relaying schemes, with secure beamforming, is shown
over direct transmission. It is also shown that the best relaying scheme
depends on how far the eavesdropper is located from the transmitter and the
relays, the number of relays, and their geometric layout
On the Secrecy Rate of Spatial Modulation Based Indoor Visible Light Communications
In this paper, we investigate the physical-layer security for a spatial
modulation (SM) based indoor visible light communication (VLC) system, which
includes multiple transmitters, a legitimate receiver, and a passive
eavesdropper (Eve). At the transmitters, the SM scheme is employed, i.e., only
one transmitter is active at each time instant. To choose the active
transmitter, a uniform selection (US) scheme is utilized. Two scenarios are
considered: one is with non-negativity and average optical intensity
constraints, the other is with non-negativity, average optical intensity and
peak optical intensity constraints. Then, lower and upper bounds on the secrecy
rate are derived for these two scenarios. Besides, the asymptotic behaviors for
the derived secrecy rate bounds at high signal-to-noise ratio (SNR) are
analyzed. To further improve the secrecy performance, a channel adaptive
selection (CAS) scheme and a greedy selection (GS) scheme are proposed to
select the active transmitter. Numerical results show that the lower and upper
bounds of the secrecy rate are tight. At high SNR, small asymptotic performance
gaps exist between the derived lower and upper bounds. Moreover, the proposed
GS scheme has the best performance, followed by the CAS scheme and the US
scheme.Comment: 30 pages, 10 figures, accepted by IEEE Journal on Selected Areas in
Communications, 201