987 research outputs found
Achieving secrecy without knowing the number of eavesdropper antennas
The existing research on physical layer security commonly assumes the number
of eavesdropper antennas to be known. Although this assumption allows one to
easily compute the achievable secrecy rate, it can hardly be realized in
practice. In this paper, we provide an innovative approach to study secure
communication systems without knowing the number of eavesdropper antennas by
introducing the concept of spatial constraint into physical layer security.
Specifically, the eavesdropper is assumed to have a limited spatial region to
place (possibly an infinite number of) antennas. From a practical point of
view, knowing the spatial constraint of the eavesdropper is much easier than
knowing the number of eavesdropper antennas. We derive the achievable secrecy
rates of the spatially-constrained system with and without friendly jamming. We
show that a non-zero secrecy rate is achievable with the help of a friendly
jammer, even if the eavesdropper places an infinite number of antennas in its
spatial region. Furthermore, we find that the achievable secrecy rate does not
monotonically increase with the jamming power, and hence, we obtain the
closed-form solution of the optimal jamming power that maximizes the secrecy
rate.Comment: IEEE transactions on wireless communications, accepted to appea
Secure Two-Way Transmission via Wireless-Powered Untrusted Relay and External Jammer
In this paper, we propose a two-way secure communication scheme where two
transceivers exchange confidential messages via a wireless powered untrusted
amplify-and-forward (AF) relay in the presence of an external jammer. We take
into account both friendly jamming (FJ) and Gaussian noise jamming (GNJ)
scenarios. Based on the time switching (TS) architecture at the relay, the data
transmission is done in three phases. In the first phase, both the
energy-starved nodes, the untrustworthy relay and the jammer, are charged by
non-information radio frequency (RF) signals from the sources. In the second
phase, the two sources send their information signals and concurrently, the
jammer transmits artificial noise to confuse the curious relay. Finally, the
third phase is dedicated to forward a scaled version of the received signal
from the relay to the sources. For the proposed secure transmission schemes, we
derive new closed-form lower-bound expressions for the ergodic secrecy sum rate
(ESSR) in the high signal-to-noise ratio (SNR) regime. We further analyze the
asymptotic ESSR to determine the key parameters; the high SNR slope and the
high SNR power offset of the jamming based scenarios. To highlight the
performance advantage of the proposed FJ, we also examine the scenario of
without jamming (WoJ). Finally, numerical examples and discussions are provided
to acquire some engineering insights, and to demonstrate the impacts of
different system parameters on the secrecy performance of the considered
communication scenarios. The numerical results illustrate that the proposed FJ
significantly outperforms the traditional one-way communication and the
Constellation rotation approach, as well as our proposed benchmarks, the
two-way WoJ and GNJ scenarios.Comment: 14 pages, 6 figures, Submitted to IEEE Transactions on Vehicular
Technolog
Secure Communication with a Wireless-Powered Friendly Jammer
In this paper, we propose to use a wireless-powered friendly jammer to enable
secure communication between a source node and destination node, in the
presence of an eavesdropper. We consider a two-phase communication protocol
with fixed-rate transmission. In the first phase, wireless power transfer is
conducted from the source to the jammer. In the second phase, the source
transmits the information-bearing signal under the protection of a jamming
signal sent by the jammer using the harvested energy in the first phase. We
analytically characterize the long-time behavior of the proposed protocol and
derive a closed-form expression for the throughput. We further optimize the
rate parameters for maximizing the throughput subject to a secrecy outage
probability constraint. Our analytical results show that the throughput
performance differs significantly between the single-antenna jammer case and
the multi-antenna jammer case. For instance, as the source transmit power
increases, the throughput quickly reaches an upper bound with single-antenna
jammer, while the throughput grows unbounded with multi-antenna jammer. Our
numerical results also validate the derived analytical results.Comment: accepted for publication in IEEE Transactions on Wireless
Communication
Cooperative Secure Transmission by Exploiting Social Ties in Random Networks
Social awareness and social ties are becoming increasingly popular with
emerging mobile and handheld devices. Social trust degree describing the
strength of the social ties has drawn lots of research interests in many fields
in wireless communications, such as resource sharing, cooperative communication
and so on. In this paper, we propose a hybrid cooperative beamforming and
jamming scheme to secure communication based on the social trust degree under a
stochastic geometry framework. The friendly nodes are categorized into relays
and jammers according to their locations and social trust degrees with the
source node. We aim to analyze the involved connection outage probability (COP)
and secrecy outage probability (SOP) of the performance in the networks. To
achieve this target, we propose a double Gamma ratio (DGR) approach through
Gamma approximation. Based on this, the COP and SOP are tractably obtained in
closed-form. We further consider the SOP in the presence of Poisson Point
Process (PPP) distributed eavesdroppers and derive an upper bound. The
simulation results verify our theoretical findings, and validate that the
social trust degree has dramatic influences on the security performance in the
networks.Comment: 30 pages, 11 figures, to be published in IEEE Transactions on
Communication
Exploiting Full-duplex Receivers for Achieving Secret Communications in Multiuser MISO Networks
We consider a broadcast channel, in which a multi-antenna transmitter (Alice)
sends confidential information signals to legitimate users (Bobs) in
the presence of eavesdroppers (Eves). Alice uses MIMO precoding to generate
the information signals along with her own (Tx-based) friendly jamming.
Interference at each Bob is removed by MIMO zero-forcing. This, however, leaves
a "vulnerability region" around each Bob, which can be exploited by a nearby
Eve. We address this problem by augmenting Tx-based friendly jamming (TxFJ)
with Rx-based friendly jamming (RxFJ), generated by each Bob. Specifically,
each Bob uses self-interference suppression (SIS) to transmit a friendly
jamming signal while simultaneously receiving an information signal over the
same channel. We minimize the powers allocated to the information, TxFJ, and
RxFJ signals under given guarantees on the individual secrecy rate for each
Bob. The problem is solved for the cases when the eavesdropper's channel state
information is known/unknown. Simulations show the effectiveness of the
proposed solution. Furthermore, we discuss how to schedule transmissions when
the rate requirements need to be satisfied on average rather than
instantaneously. Under special cases, a scheduling algorithm that serves only
the strongest receivers is shown to outperform the one that schedules all
receivers.Comment: IEEE Transactions on Communication
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