26-05-2012, 11:17 AM
Secure Communications Over Wireless Broadcast
Networks: Stability and Utility Maximization
Secure Communications Over Wireless Broadcast Networks.pdf (Size: 1.87 MB / Downloads: 59)
Abstract
A wireless broadcast networkmodel with secrecy constraints
is investigated, in which a source node broadcasts confidentialmessage
flows to user nodes, with each message intended
to be decoded accurately by one user and to be kept secret from all
other users (who are thus considered to be eavesdroppers with regard
to all other messages but their own). The source maintains a
queue for each message flow if it is not served immediately. The
channel from the source to the users is modeled as a fading
broadcast channel, and the channel state information is assumed
to be known to the source and the corresponding receivers. Two
eavesdropping models are considered. For a collaborative eavesdropping
model, in which the eavesdroppers exchange their outputs.
INTRODUCTION
WIRELESS broadcast networks constitute one class of
basic and important wireless networks, in which a
source node simultaneously transmits a number of information
flows (messages) to different destinations. However, broadcast
communications make use of the open nature of the wireless
medium, which presents a great challenge to achieve secure
communication for individual users. This is because information
for all users is contained in one transmitted signal, and
hence information destined for one user may be obtained by
nonintended users unless special coding is used. Physical layer
security, which uses randomness of a physical communication
channel to provide security for messages transmitted through
the channel, opens a promising new direction toward solving
wireless networking security problems. This approach was
pioneered by Wyner in [1] and by Csiszár and Körner in [2],
and more recently has been extensively explored in the literature
(see [3] for a review of recent advances in physical layer
security).
CHANNEL MODEL
We consider the -user fading broadcast network (see
Fig. 1), in which a source node transmits confidential messages
to user nodes. Each message is intended for one user
and needs to be kept secret from all other nodes. Hence, with
regard to one message, all users other than its intended receiver
are considered to be eavesdroppers.
CONCLUSIONS
In this paper, we have studied wireless broadcast networks,
for which we have obtained the secrecy capacity region for the
collaborative eavesdropping model and inner and outer bounds
on the secrecy capacity region for the noncollaborative eavesdropping
model. We have also obtained a secrecy throughput
optimal scheduling scheme and a corresponding jointly optimal
power control policy for the collaborative eavesdroppingmodel.
For the noncollaborative eavesdropping model, we have obtained
results similar to the above based on an achievable secrecy
rate region. For both models, we have further obtained
the rate control vector for the source node to generate messages
for users that achieve overall network utility maximization. To
the authors’ knowledge, this is the first work that addresses reliability,
security (via a physical layer approach), and stability
jointly and studies utility network maximization under these
constraints for wireless broadcast networks. The approach in
this paper can be applied to analyze other wireless networks including
multiple-access, interference, and relay networks. This
approach also allows the incorporation of public and common
message flows for users in the system as well.