|dc.description.abstract||Security and privacy have become increasingly significant concerns in wireless communication
networks, due to the open nature of the wireless medium which makes the wireless
transmission vulnerable to eavesdropping and inimical attacking. The emergence and
development of decentralized and ad-hoc wireless networks pose great challenges to the
implementation of higher-layer key distribution and management in practice. Against
this background, physical layer security has emerged as an attractive approach for performing
secure transmission in a low complexity manner. This thesis concentrates on
physical layer security design and enhancement in wireless networks.
First, this thesis presents a new unifying framework to analyze the average secrecy
capacity and secrecy outage probability. Besides the exact average secrecy capacity
and secrecy outage probability, a new approach for analyzing the asymptotic behavior is
proposed to compute key performance parameters such as high signal-to-noise ratio slope,
power offset, secrecy diversity order, and secrecy array gain. Typical fading environments
such as two-wave with diffuse power and Nakagami-m are taken into account.
Second, an analytical framework of using antenna selection schemes to achieve secrecy
is provided. In particular, transmit antenna selection and generalized selection combining
are considered including its special cases of selection combining and maximal-ratio
Third, the fundamental questions surrounding the joint impact of power constraints on
the cognitive wiretap channel are addressed. Important design insights are revealed
regarding the interplay between two power constraints, namely the maximum transmit
at the secondary network and the peak interference power at the primary network.
Fourth, secure single carrier transmission is considered in the two-hop decode-andi
forward relay networks. A two-stage relay and destination selection is proposed to minimize
the eavesdropping and maximize the signal power of the link between the relay and
the destination. In two-hop amplify-and-forward untrusted relay networks, secrecy may
not be guaranteed even in the absence of external eavesdroppers. As such, cooperative
jamming with optimal power allocation is proposed to achieve non-zero secrecy rate.
Fifth and last, physical layer security in large-scale wireless sensor networks is introduced.
A stochastic geometry approach is adopted to model the positions of sensors, access
points, sinks, and eavesdroppers. Two scenarios are considered: i) the active sensors
transmit their sensing data to the access points, and ii) the active access points forward
the data to the sinks. Important insights are concluded.||en_US