17,165 research outputs found
Reliability of Mobile Agents for Reliable Service Discovery Protocol in MANET
Recently mobile agents are used to discover services in mobile ad-hoc network
(MANET) where agents travel through the network, collecting and sometimes
spreading the dynamically changing service information. But it is important to
investigate how reliable the agents are for this application as the
dependability issues(reliability and availability) of MANET are highly affected
by its dynamic nature.The complexity of underlying MANET makes it hard to
obtain the route reliability of the mobile agent systems (MAS); instead we
estimate it using Monte Carlo simulation. Thus an algorithm for estimating the
task route reliability of MAS (deployed for discovering services) is proposed,
that takes into account the effect of node mobility in MANET. That mobility
pattern of the nodes affects the MAS performance is also shown by considering
different mobility models. Multipath propagation effect of radio signal is
considered to decide link existence. Transient link errors are also considered.
Finally we propose a metric to calculate the reliability of service discovery
protocol and see how MAS performance affects the protocol reliability. The
experimental results show the robustness of the proposed algorithm. Here the
optimum value of network bandwidth (needed to support the agents) is calculated
for our application. However the reliability of MAS is highly dependent on link
failure probability
On Leveraging Partial Paths in Partially-Connected Networks
Mobile wireless network research focuses on scenarios at the extremes of the
network connectivity continuum where the probability of all nodes being
connected is either close to unity, assuming connected paths between all nodes
(mobile ad hoc networks), or it is close to zero, assuming no multi-hop paths
exist at all (delay-tolerant networks). In this paper, we argue that a sizable
fraction of networks lies between these extremes and is characterized by the
existence of partial paths, i.e. multi-hop path segments that allow forwarding
data closer to the destination even when no end-to-end path is available. A
fundamental issue in such networks is dealing with disruptions of end-to-end
paths. Under a stochastic model, we compare the performance of the established
end-to-end retransmission (ignoring partial paths), against a forwarding
mechanism that leverages partial paths to forward data closer to the
destination even during disruption periods. Perhaps surprisingly, the
alternative mechanism is not necessarily superior. However, under a stochastic
monotonicity condition between current v.s. future path length, which we
demonstrate to hold in typical network models, we manage to prove superiority
of the alternative mechanism in stochastic dominance terms. We believe that
this study could serve as a foundation to design more efficient data transfer
protocols for partially-connected networks, which could potentially help
reducing the gap between applications that can be supported over disconnected
networks and those requiring full connectivity.Comment: Extended version of paper appearing at IEEE INFOCOM 2009, April
20-25, Rio de Janeiro, Brazi
A robust self-organized public key management for mobile ad hoc networks
A mobile ad hoc network (MANET) is a self-organized wireless network where mobile nodes can communicate with each other without the use of any existing network infrastructure or centralized administration. Trust establishment and management are essential for any security framework of MANETs. However, traditional solutions to key management through accessing trusted authorities or centralized servers are infeasible for MANETs due to the absence of infrastructure, frequent mobility, and wireless link instability. In this paper, we propose a robust self-organized, public key management for MANETs. The proposed scheme relies on establishing a small number of trust relations between neighboring nodes during the network initialization phase. Experiences gained as a result of successful communications and node mobility through the network enhance the formation of a web of trust between mobile nodes. The proposed scheme allows each user to create its public key and the corresponding private key, to issue certificates to neighboring nodes, and to perform public key authentication through at least two independent certificate chains without relying on any centralized authority. A measure of the communications cost of the key distribution process has been proposed. Simulation results show that the proposed scheme is robust and efficient in the mobility environment of MANET and against malicious node attacks
Quantifying Link Stability in Ad Hoc Wireless Networks Subject to Ornstein-Uhlenbeck Mobility
The performance of mobile ad hoc networks in general and that of the routing
algorithm, in particular, can be heavily affected by the intrinsic dynamic
nature of the underlying topology. In this paper, we build a new
analytical/numerical framework that characterizes nodes' mobility and the
evolution of links between them. This formulation is based on a stationary
Markov chain representation of link connectivity. The existence of a link
between two nodes depends on their distance, which is governed by the mobility
model. In our analysis, nodes move randomly according to an Ornstein-Uhlenbeck
process using one tuning parameter to obtain different levels of randomness in
the mobility pattern. Finally, we propose an entropy-rate-based metric that
quantifies link uncertainty and evaluates its stability. Numerical results show
that the proposed approach can accurately reflect the random mobility in the
network and fully captures the link dynamics. It may thus be considered a
valuable performance metric for the evaluation of the link stability and
connectivity in these networks.Comment: 6 pages, 4 figures, Submitted to IEEE International Conference on
Communications 201
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
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