2,670 research outputs found
Secret message capacity of a line network
We investigate the problem of information theoretically secure communication
in a line network with erasure channels and state feedback. We consider a
spectrum of cases for the private randomness that intermediate nodes can
generate, ranging from having intermediate nodes generate unlimited private
randomness, to having intermediate nodes generate no private randomness, and
all cases in between. We characterize the secret message capacity when either
only one of the channels is eavesdropped or all of the channels are
eavesdropped, and we develop polynomial time algorithms that achieve these
capacities. We also give an outer bound for the case where an arbitrary number
of channels is eavesdropped. Our work is the first to characterize the secrecy
capacity of a network of arbitrary size, with imperfect channels and feedback.
As a side result, we derive the secret key and secret message capacity of an
one-hop network, when the source has limited randomness
Flat Cellular (UMTS) Networks
Traditionally, cellular systems have been built in a hierarchical manner: many specialized cellular access network elements that collectively form a hierarchical cellular system. When 2G and later 3G systems were designed there was a good reason to make system hierarchical: from a cost-perspective it was better to concentrate traffic and to share the cost of processing equipment over a large set of users while keeping the base stations relatively cheap. However, we believe the economic reasons for designing cellular systems in a hierarchical manner have disappeared: in fact, hierarchical architectures hinder future efficient deployments. In this paper, we argue for completely flat cellular wireless systems, which need just one type of specialized network element to provide radio access network (RAN) functionality, supplemented by standard IP-based network elements to form a cellular network. While the reason for building a cellular system in a hierarchical fashion has disappeared, there are other good reasons to make the system architecture flat: (1) as wireless transmission techniques evolve into hybrid ARQ systems, there is less need for a hierarchical cellular system to support spatial diversity; (2) we foresee that future cellular networks are part of the Internet, while hierarchical systems typically use interfaces between network elements that are specific to cellular standards or proprietary. At best such systems use IP as a transport medium, not as a core component; (3) a flat cellular system can be self scaling while a hierarchical system has inherent scaling issues; (4) moving all access technologies to the edge of the network enables ease of converging access technologies into a common packet core; and (5) using an IP common core makes the cellular network part of the Internet
A Survey on Wireless Security: Technical Challenges, Recent Advances and Future Trends
This paper examines the security vulnerabilities and threats imposed by the
inherent open nature of wireless communications and to devise efficient defense
mechanisms for improving the wireless network security. We first summarize the
security requirements of wireless networks, including their authenticity,
confidentiality, integrity and availability issues. Next, a comprehensive
overview of security attacks encountered in wireless networks is presented in
view of the network protocol architecture, where the potential security threats
are discussed at each protocol layer. We also provide a survey of the existing
security protocols and algorithms that are adopted in the existing wireless
network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term
evolution (LTE) systems. Then, we discuss the state-of-the-art in
physical-layer security, which is an emerging technique of securing the open
communications environment against eavesdropping attacks at the physical layer.
We also introduce the family of various jamming attacks and their
counter-measures, including the constant jammer, intermittent jammer, reactive
jammer, adaptive jammer and intelligent jammer. Additionally, we discuss the
integration of physical-layer security into existing authentication and
cryptography mechanisms for further securing wireless networks. Finally, some
technical challenges which remain unresolved at the time of writing are
summarized and the future trends in wireless security are discussed.Comment: 36 pages. Accepted to Appear in Proceedings of the IEEE, 201
Practical Provably Secure Multi-node Communication
We present a practical and provably-secure multimode communication scheme in
the presence of a passive eavesdropper. The scheme is based on a random
scheduling approach that hides the identity of the transmitter from the
eavesdropper. This random scheduling leads to ambiguity at the eavesdropper
with regard to the origin of the transmitted frame. We present the details of
the technique and analyze it to quantify the secrecy-fairness-overhead
trade-off. Implementation of the scheme over Crossbow Telosb motes, equipped
with CC2420 radio chips, shows that the scheme can achieve significant secrecy
gain with vanishing outage probability. In addition, it has significant
overhead advantage over direct extensions to two-nodes schemes. The technique
also has the advantage of allowing inactive nodes to leverage sleep mode to
further save energy.Comment: Proceedings of the IEEE International Conference on Computing,
Networking and Communications (ICNC 2014
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