56 research outputs found
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
On the Compound MIMO Broadcast Channels with Confidential Messages
We study the compound multi-input multi-output (MIMO) broadcast channel with
confidential messages (BCC), where one transmitter sends a common message to
two receivers and two confidential messages respectively to each receiver. The
channel state may take one of a finite set of states, and the transmitter knows
the state set but does not know the realization of the state. We study
achievable rates with perfect secrecy in the high SNR regime by characterizing
an achievable secrecy degree of freedom (s.d.o.f.) region for two models, the
Gaussian MIMO-BCC and the ergodic fading multi-input single-output (MISO)-BCC
without a common message. We show that by exploiting an additional temporal
dimension due to state variation in the ergodic fading model, the achievable
s.d.o.f. region can be significantly improved compared to the Gaussian model
with a constant state, although at the price of a larger delay.Comment: To appear in Proc. IEEE Symposium on Information Theory (ISIT 2009)
June 28 - July 3, 2009, Seoul, Kore
On SDoF of Multi-Receiver Wiretap Channel With Alternating CSIT
We study the problem of secure transmission over a Gaussian multi-input
single-output (MISO) two receiver channel with an external eavesdropper, under
the assumption that the state of the channel which is available to each
receiver is conveyed either perfectly () or with delay () to the
transmitter. Denoting by , , and the channel state information
at the transmitter (CSIT) of user 1, user 2, and eavesdropper, respectively,
the overall CSIT can then alternate between eight possible states, i.e.,
. We denote by the
fraction of time during which the state occurs. Under these
assumptions, we first consider the Gaussian MISO wiretap channel and
characterize the secure degrees of freedom (SDoF). Next, we consider the
general multi-receiver setup and characterize the SDoF region of fixed hybrid
states , , and . We then focus our attention on the symmetric
case in which . For this case, we establish bounds
on SDoF region. The analysis reveals that alternating CSIT allows synergistic
gains in terms of SDoF; and shows that, by opposition to encoding separately
over different states, joint encoding across the states enables strictly better
secure rates. Furthermore, we specialize our results for the two receivers
channel with an external eavesdropper to the two-user broadcast channel. We
show that, the synergistic gains in terms of SDoF by alternating CSIT is not
restricted to multi-receiver wiretap channels; and, can also be harnessed under
broadcast setting.Comment: To Appear in IEEE Transactions on Information Forensics and Securit
On the Secrecy Degrees of Freedom of Multi-Antenna Wiretap Channels with Delayed CSIT
The secrecy degrees of freedom (SDoF) of the Gaussian multiple-input and
single-output (MISO) wiretap channel is studied under the assumption that
delayed channel state information (CSI) is available at the transmitter and
each receiver knows its own instantaneous channel. We first show that a
strictly positive SDoF can be guaranteed whenever the transmitter has delayed
CSI (either on the legitimate channel or/and the eavesdropper channel). In
particular, in the case with delayed CSI on both channels, it is shown that the
optimal SDoF is 2/3. We then generalize the result to the two-user Gaussian
MISO broadcast channel with confidential messages and characterize the SDoF
region when the transmitter has delayed CSI of both receivers. Interestingly,
the artificial noise schemes exploiting several time instances are shown to
provide the optimal SDoF region by masking the confidential message to the
unintended receiver while aligning the interference at each receiver.Comment: 5 pages, 1 figure, 1 table. This work has been presented at ISIT
2011. The current version fixes several bugs in the Proceeding
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
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