68 research outputs found
Constrained Secrecy Capacity of Finite-Input Intersymbol Interference Wiretap Channels
We consider reliable and secure communication over intersymbol interference
wiretap channels (ISI-WTCs). In particular, we first examine the setup where
the source at the input of an ISI-WTC is unconstrained and then, based on a
general achievability result for arbitrary wiretap channels, we derive an
achievable secure rate for this ISI-WTC. Afterwards, we examine the setup where
the source at the input of an ISI-WTC is constrained to be a finite-state
machine source (FSMS) of a certain order and structure. Optimizing the
parameters of this FSMS toward maximizing the secure rate is a computationally
intractable problem in general, and so, toward finding a local maximum, we
propose an iterative algorithm that at every iteration replaces the secure rate
function by a suitable surrogate function whose maximum can be found
efficiently. Although the secure rates achieved in the unconstrained setup are
potentially larger than the secure rates achieved in the constraint setup, the
latter setup has the advantage of leading to efficient algorithms for
estimating achievable secure rates and also has the benefit of being the basis
of efficient encoding and decoding schemes.Comment: 32 pages, 6 figure
Mathematical control of complex systems 2013
Mathematical control of complex systems have already become an ideal research area for control engineers, mathematicians, computer scientists, and biologists to understand, manage, analyze, and interpret functional information/dynamical behaviours from real-world complex dynamical systems, such as communication systems, process control, environmental systems, intelligent manufacturing systems, transportation systems, and structural systems. This special issue aims to bring together the latest/innovative knowledge and advances in mathematics for handling complex systems. Topics include, but are not limited to the following: control systems theory (behavioural systems, networked control systems, delay systems, distributed systems, infinite-dimensional systems, and positive systems); networked control (channel capacity constraints, control over communication networks, distributed filtering and control, information theory and control, and sensor networks); and stochastic systems (nonlinear filtering, nonparametric methods, particle filtering, partial identification, stochastic control, stochastic realization, system identification)
On–Off-Based Secure Transmission Design With Outdated Channel State Information
We design new secure on-off transmission schemes
in wiretap channels with outdated channel state information
(CSI). In our design we consider not only the outdated CSI from
the legitimate receiver but two distinct scenarios, depending on
whether or not the outdated CSI from the eavesdropper is known
at the transmitter. Under this consideration our schemes exploit
the useful knowledge contained in the available outdated CSI,
based on which the transmitter decides whether to transmit or
not. We derive new closed-form expressions for the transmission
probability, the connection outage probability, the secrecy outage
probability, and the reliable and secure transmission probability
to characterize the achievable performance. Based on these
results, we present the optimal solutions that maximize the
secrecy throughput under dual connection and secrecy outage
constraints. Our analytical and numerical results offer detailed
insights into the design of the wiretap coding parameters and
the imposed outage constraints. We further show that allowing
more freedom on the codeword transmission rate enables a larger
feasible region of the dual outage constraints by exploiting the
trade-off between reliability and security.ARC Discovery Projects Grant DP15010390
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
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