2,856 research outputs found
Exact Optimized-cost Repair in Multi-hop Distributed Storage Networks
The problem of exact repair of a failed node in multi-hop networked
distributed storage systems is considered. Contrary to the most of the current
studies which model the repair process by the direct links from surviving nodes
to the new node, the repair is modeled by considering the multi-hop network
structure, and taking into account that there might not exist direct links from
all the surviving nodes to the new node. In the repair problem of these
systems, surviving nodes may cooperate to transmit the repair traffic to the
new node. In this setting, we define the total number of packets transmitted
between nodes as repair-cost. A lower bound of the repaircost can thus be found
by cut-set bound analysis. In this paper, we show that the lower bound of the
repair-cost is achievable for the exact repair of MDS codes in tandem and grid
networks, thus resulting in the minimum-cost exact MDS codes. Further, two
suboptimal (achievable) bounds for the large scale grid networks are proposed.Comment: (To appear in ICC 2014
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,
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