47 research outputs found
Near-Optimal Modulo-and-Forward Scheme for the Untrusted Relay Channel
This paper studies an untrusted relay channel, in which the destination sends
artificial noise simultaneously with the source sending a message to the relay,
in order to protect the source's confidential message. The traditional
amplify-and-forward (AF) scheme shows poor performance in this situation
because of the interference power dilemma: providing better security by using
stronger artificial noise will decrease the confidential message power from the
relay to the destination. To solve this problem, a modulo-and-forward (MF)
operation at the relay with nested lattice encoding at the source is proposed.
For this system with full channel state information at the transmitter (CSIT),
theoretical analysis shows that the proposed MF scheme approaches the secrecy
capacity within 1/2 bit for any channel realization, and hence achieves full
generalized security degrees of freedom (G-SDoF). In contrast, the AF scheme
can only achieve a small fraction of the G-SDoF. For this system without any
CSIT, the total outage event, defined as either connection outage or secrecy
outage, is introduced. Based on this total outage definition, analysis shows
that the proposed MF scheme achieves the full generalized secure diversity gain
(G-SDG) of order one. On the other hand, the AF scheme can only achieve a G-SDG
of 1/2 at most
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201
Secure Retrospective Interference Alignment
In this paper, the -user interference channel with secrecy constraints is
considered with delayed channel state information at transmitters (CSIT). We
propose a novel secure retrospective interference alignment scheme in which the
transmitters carefully mix information symbols with artificial noises to ensure
confidentiality. Achieving positive secure degrees of freedom (SDoF) is
challenging due to the delayed nature of CSIT, and the distributed nature of
the transmitters. Our scheme works over two phases: phase one in which each
transmitter sends information symbols mixed with artificial noises, and repeats
such transmission over multiple rounds. In the next phase, each transmitter
uses delayed CSIT of the previous phase and sends a function of the net
interference and artificial noises (generated in previous phase), which is
simultaneously useful for all receivers. These phases are designed to ensure
the decodability of the desired messages while satisfying the secrecy
constraints. We present our achievable scheme for three models, namely: 1)
-user interference channel with confidential messages (IC-CM), and we show
that SDoF is achievable, 2) -user interference
channel with an external eavesdropper (IC-EE), and 3) -user IC with
confidential messages and an external eavesdropper (IC-CM-EE). We show that for
the -user IC-EE, SDoF is achievable, and for
the -user IC-CM-EE, is achievable. To the best
of our knowledge, this is the first result on the -user interference channel
with secrecy constrained models and delayed CSIT that achieves a SDoF which
scales with , the number of users.Comment: Submitted to IEEE Transactions on Wireless Communication