13 research outputs found
Towards the Secrecy Capacity of the Gaussian MIMO Wire-tap Channel: The 2-2-1 Channel
We find the secrecy capacity of the 2-2-1 Gaussian MIMO wire-tap channel,
which consists of a transmitter and a receiver with two antennas each, and an
eavesdropper with a single antenna. We determine the secrecy capacity of this
channel by proposing an achievable scheme and then developing a tight upper
bound that meets the proposed achievable secrecy rate. We show that, for this
channel, Gaussian signalling in the form of beam-forming is optimal, and no
pre-processing of information is necessary.Comment: Submitted to IEEE Transactions on Information Theor
Waveform Design for Secure SISO Transmissions and Multicasting
Wireless physical-layer security is an emerging field of research aiming at
preventing eavesdropping in an open wireless medium. In this paper, we propose
a novel waveform design approach to minimize the likelihood that a message
transmitted between trusted single-antenna nodes is intercepted by an
eavesdropper. In particular, with knowledge first of the eavesdropper's channel
state information (CSI), we find the optimum waveform and transmit energy that
minimize the signal-to-interference-plus-noise ratio (SINR) at the output of
the eavesdropper's maximum-SINR linear filter, while at the same time provide
the intended receiver with a required pre-specified SINR at the output of its
own max-SINR filter. Next, if prior knowledge of the eavesdropper's CSI is
unavailable, we design a waveform that maximizes the amount of energy available
for generating disturbance to eavesdroppers, termed artificial noise (AN),
while the SINR of the intended receiver is maintained at the pre-specified
level. The extensions of the secure waveform design problem to multiple
intended receivers are also investigated and semidefinite relaxation (SDR) -an
approximation technique based on convex optimization- is utilized to solve the
arising NP-hard design problems. Extensive simulation studies confirm our
analytical performance predictions and illustrate the benefits of the designed
waveforms on securing single-input single-output (SISO) transmissions and
multicasting
Cooperative jamming via spectrum leasing
Abstract—Secure communication rates can be facilitated or enhanced via deployment of cooperative jammers in a multi-terminal environment. Such an approach typically assumes ded-icated and/or altruistic jamming nodes, investing their resources for the good of the whole system. In this paper, we demonstrate that jammers can be recruited to provide significant improve-ments of secrecy rates even when this assumption is alleviated. A game-theoretic framework is proposed where a source node, towards the maximization of its secrecy rate, utilizes the jamming services from a set of non-altruistic nodes, compensating them with a fraction of its bandwidth for transmission of their user data. With the goal of maximizing their user-data transmission rate priced by the invested power, potential cooperative jammers will provide the jamming/transmitting power that is generally proportional to the amount of leased bandwidth. Elaborating initially on a single-jammer scenario, interaction between the source and a cooperative jammer is modeled as the Stackelberg leader-follower game. The scheme is further extended to involve multiple potential jammers, applying competition mechanisms such as the auctioning and power control game, while maintain-ing the Stackelberg framework. I
Cooperation with an Untrusted Relay: A Secrecy Perspective
We consider the communication scenario where a source-destination pair wishes
to keep the information secret from a relay node despite wanting to enlist its
help. For this scenario, an interesting question is whether the relay node
should be deployed at all. That is, whether cooperation with an untrusted relay
node can ever be beneficial. We first provide an achievable secrecy rate for
the general untrusted relay channel, and proceed to investigate this question
for two types of relay networks with orthogonal components. For the first
model, there is an orthogonal link from the source to the relay. For the second
model, there is an orthogonal link from the relay to the destination. For the
first model, we find the equivocation capacity region and show that answer is
negative. In contrast, for the second model, we find that the answer is
positive. Specifically, we show by means of the achievable secrecy rate based
on compress-and-forward, that, by asking the untrusted relay node to relay
information, we can achieve a higher secrecy rate than just treating the relay
as an eavesdropper. For a special class of the second model, where the relay is
not interfering itself, we derive an upper bound for the secrecy rate using an
argument whose net effect is to separate the eavesdropper from the relay. The
merit of the new upper bound is demonstrated on two channels that belong to
this special class. The Gaussian case of the second model mentioned above
benefits from this approach in that the new upper bound improves the previously
known bounds. For the Cover-Kim deterministic relay channel, the new upper
bound finds the secrecy capacity when the source-destination link is not worse
than the source-relay link, by matching with the achievable rate we present.Comment: IEEE Transactions on Information Theory, submitted October 2008,
revised October 2009. This is the revised versio