4,452 research outputs found
Capacity of Wireless Distributed Storage Systems with Broadcast Repair
In wireless distributed storage systems, storage nodes are connected by
wireless channels, which are broadcast in nature. This paper exploits this
unique feature to design an efficient repair mechanism, called broadcast
repair, for wireless distributed storage systems in the presence of
multiple-node failures. Due to the broadcast nature of wireless transmission,
we advocate a new measure on repair performance called repair-transmission
bandwidth. In contrast to repair bandwidth, which measures the average number
of packets downloaded by a newcomer to replace a failed node,
repair-transmission bandwidth measures the average number of packets
transmitted by helper nodes per failed node. A fundamental study on the storage
capacity of wireless distributed storage systems with broadcast repair is
conducted by modeling the storage system as a multicast network and analyzing
the minimum cut of the corresponding information flow graph. The fundamental
tradeoff between storage efficiency and repair-transmission bandwidth is also
obtained for functional repair. The performance of broadcast repair is compared
both analytically and numerically with that of cooperative repair, the basic
repair method for wired distributed storage systems with multiple-node
failures. While cooperative repair is based on the idea of allowing newcomers
to exchange packets, broadcast repair is based on the idea of allowing a helper
to broadcast packets to all newcomers simultaneously. We show that broadcast
repair outperforms cooperative repair, offering a better tradeoff between
storage efficiency and repair-transmission bandwidth.Comment: 28 pages, 7 figure
Secure Partial Repair in Wireless Caching Networks with Broadcast Channels
We study security in partial repair in wireless caching networks where parts
of the stored packets in the caching nodes are susceptible to be erased. Let us
denote a caching node that has lost parts of its stored packets as a sick
caching node and a caching node that has not lost any packet as a healthy
caching node. In partial repair, a set of caching nodes (among sick and healthy
caching nodes) broadcast information to other sick caching nodes to recover the
erased packets. The broadcast information from a caching node is assumed to be
received without any error by all other caching nodes. All the sick caching
nodes then are able to recover their erased packets, while using the broadcast
information and the nonerased packets in their storage as side information. In
this setting, if an eavesdropper overhears the broadcast channels, it might
obtain some information about the stored file. We thus study secure partial
repair in the senses of information-theoretically strong and weak security. In
both senses, we investigate the secrecy caching capacity, namely, the maximum
amount of information which can be stored in the caching network such that
there is no leakage of information during a partial repair process. We then
deduce the strong and weak secrecy caching capacities, and also derive the
sufficient finite field sizes for achieving the capacities. Finally, we propose
optimal secure codes for exact partial repair, in which the recovered packets
are exactly the same as erased packets.Comment: To Appear in IEEE Conference on Communication and Network Security
(CNS
Storage-Repair Bandwidth Trade-off for Wireless Caching with Partial Failure and Broadcast Repair
Repair of multiple partially failed cache nodes is studied in a distributed
wireless content caching system, where out of a total of cache nodes
lose part of their cached data. Broadcast repair of failed cache contents at
the network edge is studied; that is, the surviving cache nodes transmit
broadcast messages to the failed ones, which are then used, together with the
surviving data in their local cache memories, to recover the lost content. The
trade-off between the storage capacity and the repair bandwidth is derived. It
is shown that utilizing the broadcast nature of the wireless medium and the
surviving cache contents at partially failed nodes significantly reduces the
required repair bandwidth per node.Comment: Conference version of this paper has been submitted for review in ITW
2018. This submission includes the proof of theorem
Practical Functional Regenerating Codes for Broadcast Repair of Multiple Nodes
A code construction and repair scheme for optimal functional regeneration of
multiple node failures is presented, which is based on stitching together short
MDS codes on carefully chosen sets of points lying on a linearized polynomial.
The nodes are connected wirelessly, hence all transmissions by helper nodes
during a repair round are available to all the nodes being repaired. The scheme
is simple and practical because of low subpacketization, low I/O cost and low
computational cost. Achievability of the minimum-bandwidth regenerating (MBR)
point, as well as an interior point, on the optimal storage-repair bandwidth
tradeoff curve is shown. The subspace properties derived in the paper provide
insight into the general properties of functional regenerating codes.Comment: 5 pages, ISIT 201
Applied Erasure Coding in Networks and Distributed Storage
The amount of digital data is rapidly growing. There is an increasing use of
a wide range of computer systems, from mobile devices to large-scale data
centers, and important for reliable operation of all computer systems is
mitigating the occurrence and the impact of errors in digital data. The demand
for new ultra-fast and highly reliable coding techniques for data at rest and
for data in transit is a major research challenge. Reliability is one of the
most important design requirements. The simplest way of providing a degree of
reliability is by using data replication techniques. However, replication is
highly inefficient in terms of capacity utilization. Erasure coding has
therefore become a viable alternative to replication since it provides the same
level of reliability as replication with significantly less storage overhead.
The present thesis investigates efficient constructions of erasure codes for
different applications. Methods from both coding and information theory have
been applied to network coding, Optical Packet Switching (OPS) networks and
distributed storage systems. The following four issues are addressed: -
Construction of binary and non-binary erasure codes; - Reduction of the header
overhead due to the encoding coefficients in network coding; - Construction and
implementation of new erasure codes for large-scale distributed storage systems
that provide savings in the storage and network resources compared to
state-of-the-art codes; and - Provision of a unified view on Quality of Service
(QoS) in OPS networks when erasure codes are used, with the focus on Packet
Loss Rate (PLR), survivability and secrecy
An Overview of Mobile Ad Hoc Networks for the Existing Protocols and Applications
Mobile Ad Hoc Network (MANET) is a collection of two or more devices or nodes
or terminals with wireless communications and networking capability that
communicate with each other without the aid of any centralized administrator
also the wireless nodes that can dynamically form a network to exchange
information without using any existing fixed network infrastructure. And it's
an autonomous system in which mobile hosts connected by wireless links are free
to be dynamically and some time act as routers at the same time, and we discuss
in this paper the distinct characteristics of traditional wired networks,
including network configuration may change at any time, there is no direction
or limit the movement and so on, and thus needed a new optional path Agreement
(Routing Protocol) to identify nodes for these actions communicate with each
other path, An ideal choice way the agreement should not only be able to find
the right path, and the Ad Hoc Network must be able to adapt to changing
network of this type at any time. and we talk in details in this paper all the
information of Mobile Ad Hoc Network which include the History of ad hoc,
wireless ad hoc, wireless mobile approaches and types of mobile ad Hoc
networks, and then we present more than 13 types of the routing Ad Hoc Networks
protocols have been proposed. In this paper, the more representative of routing
protocols, analysis of individual characteristics and advantages and
disadvantages to collate and compare, and present the all applications or the
Possible Service of Ad Hoc Networks.Comment: 24 Pages, JGraph-Hoc Journa
Functional broadcast repair of multiple partial failures in wireless distributed storage systems
We consider a distributed storage system with n nodes, where a user can recover the stored file from any k nodes, and study the problem of repairing r partially failed nodes. We consider broadcast repair , that is, d surviving nodes transmit broadcast messages on an error-free wireless channel to the r nodes being repaired, which are then used, together with the surviving data in the local memories of the failed nodes, to recover the lost content. First, we derive the trade-off between the storage capacity and the repair bandwidth for partial repair of multiple failed nodes, based on the cut-set bound for information flow graphs. It is shown that utilizing the broadcast nature of the wireless medium and the surviving contents at the partially failed nodes reduces the repair bandwidth per node significantly. Then, we list a set of invariant conditions that are sufficient for a functional repair code to be feasible. We further propose a scheme for functional repair of multiple failed nodes that satisfies the invariant conditions with high probability, and its extension to the repair of partial failures. The performance of the proposed scheme meets the cut-set bound on all the points on the trade-off curve for all admissible parameters when k is divisible by r , while employing linear subpacketization, which is an important practical consideration in the design of distributed storage codes. Unlike random linear codes, which are conventionally used for functional repair of failed nodes, the proposed repair scheme has lower overhead, lower input-output cost, and lower computational complexity during repair
Secure and Private Cloud Storage Systems with Random Linear Fountain Codes
An information theoretic approach to security and privacy called Secure And
Private Information Retrieval (SAPIR) is introduced. SAPIR is applied to
distributed data storage systems. In this approach, random combinations of all
contents are stored across the network. Our coding approach is based on Random
Linear Fountain (RLF) codes. To retrieve a content, a group of servers
collaborate with each other to form a Reconstruction Group (RG). SAPIR achieves
asymptotic perfect secrecy if at least one of the servers within an RG is not
compromised. Further, a Private Information Retrieval (PIR) scheme based on
random queries is proposed. The PIR approach ensures the users privately
download their desired contents without the servers knowing about the requested
contents indices. The proposed scheme is adaptive and can provide privacy
against a significant number of colluding servers.Comment: 8 pages, 2 figure
Functional broadcast repair of multiple partial failures in wireless distributed storage systems
We consider a distributed storage system with n nodes, where a user can recover the stored file from any k nodes, and study the problem of repairing r partially failed nodes. We consider broadcast repair , that is, d surviving nodes transmit broadcast messages on an error-free wireless channel to the r nodes being repaired, which are then used, together with the surviving data in the local memories of the failed nodes, to recover the lost content. First, we derive the trade-off between the storage capacity and the repair bandwidth for partial repair of multiple failed nodes, based on the cut-set bound for information flow graphs. It is shown that utilizing the broadcast nature of the wireless medium and the surviving contents at the partially failed nodes reduces the repair bandwidth per node significantly. Then, we list a set of invariant conditions that are sufficient for a functional repair code to be feasible. We further propose a scheme for functional repair of multiple failed nodes that satisfies the invariant conditions with high probability, and its extension to the repair of partial failures. The performance of the proposed scheme meets the cut-set bound on all the points on the trade-off curve for all admissible parameters when k is divisible by r , while employing linear subpacketization, which is an important practical consideration in the design of distributed storage codes. Unlike random linear codes, which are conventionally used for functional repair of failed nodes, the proposed repair scheme has lower overhead, lower input-output cost, and lower computational complexity during repair
Stable Routing for achieving Quality of Service in wireless Sensor Networks
Networking in Wireless Sensor networks is a challenging task due to the lack
of resources in the network as well as the frequent changes in network
topology. Although lots of research has been done on supporting QoS in the
Internet and other networks, but they are not suitable for wireless sensor
networks and still QoS support for such networks remains an open problem. In
this paper, a new scheme has been proposed for achieving QoS in terms of packet
delivery, multiple connections, better power management and stable routes in
case of failure. It offers quick adaptation to distributed processing, dynamic
linking, low processing overhead and loop freedom at all times. The proposed
scheme has been incorporated using QDPRA protocol and by extensive simulation
the performance has been studied, and it is clearly shown that the proposed
scheme performs very well for different network scenarios.Comment: 7 pages,6 figures; IJCA Special Issue on MANETs, 201
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